Republic of the Philippines

Mindanao State University - Iligan Institute of Technology

Department of Ceramics, Metallurgical and
Mining Engineering
College of Engineering

NATIVE ELEMENTS
SULFIDES
SULFOSALTS

Lumancas, Gladine
Cubarol, Ruvi Jade
Gaviola, Stela Marris
Cabural, Praise Joy
Dumaguit, Sharmaine
Tomimbang, Febe Joy
Tamorite, Joule Clyde
Balacuit, Princess Sunshine
Pervandos, Clifford
Recopelacion, Advent
Vender, Jan Jerry
 NATIVE ELEMENTS

Mineral: Arsenic (As)

Composition: Arsenic, often mixed with slight amounts of antimony, nickel, silver, iron, and/or
sulfur
Color: Tin-white. Oxidizes dark gray to black. May also be banded with white lines.
Streak: Black
Hardness: 3-4
Crystal System: Hexagonal Close-packed
Specific Gravity: 5.6-5.7
Luster: Metallic
Cleavage: Basal. Cleavage is rarely observed since crystal faces are uncommon.
Fracture: Uneven
Odor: Gives off a strong, garlic odor when struck or heated.
Environment: In mesothermal veins and epithermal veins. Occasionally in metamorphic
dolomite rocks.
Rock type: Metamorphic

Uses
Arsenic is a well-known poison. Arsenic compounds are sometimes used as rat poisons and
insecticides but their use is strictly controlled.

Surprisingly, arsenic can also have medicinal applications. In Victorian times, Dr Fowler’s
Solution (potassium arsenate dissolved in water) was a popular cure-all tonic that was even used
by Charles Dickens. Today, organoarsenic compounds are added to poultry feed to prevent
disease and improve weight gain.

Arsenic is used as a doping agent in semiconductors (gallium arsenide) for solid-state devices. It
is also used in bronzing, pyrotechnics and for hardening shot.

Arsenic compounds can be used to make special glass and preserve wood.

Natural abundance
A small amount of arsenic is found in its native state. It is mainly found in minerals. The most
common arsenic-containing mineral is arsenopyrite. Others include realgar, orpiment and
enargite. Most arsenic is produced as a by-product of copper and lead refining. It can be obtained
from arsenopyrite by heating, causing the arsenic to sublime and leave behind iron(II) sulfide.

Mineral: Gold (Au)

Composition: Gold, with small amounts of silver; sometimes also copper and iron
Color: Golden yellow to Brass yellow
Streak: Golden yellow
Hardness: 2.5-3
Crystal System: Isometric (FCC / BCC)
Specific Gravity: 15.5 – 19.3
Luster: Metallic
Cleavage: None
Fracture: Hackly
Environment: In Quartz veins and high temperature hydrothermal deposits, as well as placer
deposits.
Rock type: Sedimentary, Metamorphic

Uses
Most mined gold is stored as bullion. It is also, however, used extensively in jewelry, either in its
pure form or as an alloy. The term ‘carat’ indicates the amount of gold present in an alloy. 24-
carat is pure gold, but it is very soft. 18- and 9-carat gold alloys are commonly used because they
are more durable.

The metal is also used for coinage, and has been used as standard for monetary syste ms in some
countries.

Gold can be beaten into very thin sheets (gold leaf) to be used in art, for decoration and as
architectural ornament. Electroplating can be used to cover another metal with a very thin layer
of gold. This is used in gears for watches, artificial limb joints, cheap jewellery and electrical
connectors. It is ideal for protecting electrical copper components because it conducts electricity
well and does not corrode (which would break the contact). Thin gold wires are used inside
computer chips to produce circuits.

Dentists sometimes use gold alloys in fillings, and a gold compound is used to treat some cases
of arthritis.

Gold nanoparticles are increasingly being used as industrial catalysts. Vinyl acetate, which is
used to make PVA (for glue, paint and resin), is made using a gold catalyst.

Natural abundance
Gold is one of the few elements to occur in a natural state. It is found in veins and alluvial
deposits. About 1500 tons of gold are mined each year. About two-thirds of this comes from
South Africa and most of the rest from Russia.

Mineral: Copper (Cu)

Composition: Copper, commonly associated with iron and silver
Color: Copper-red to brown. Tarnishes green, sometimes also blue, brown, red, or black.
Streak: Copper-red. Streak shiny.
Hardness: 2.5-3
Crystal System: Isometric
Specific Gravity: 8.93
Luster: Metallic
Cleavage: None
Fracture: Hackly
Environment: Most common in volcanic basalt rocks, often near the level of contact with
sedimentary rock layer. Also in hydrothermal replacement deposits and the oxidation zone of
sulfide deposits.
Rock type: Igneous, Sedimentary, Metamorphic

Uses
Historically, copper was the first metal to be worked by people. The discovery that it could be
hardened with a little tin to form the alloy bronze gave the name to the Bronze Age.

Traditionally it has been one of the metals used to make coins, along with silver and gold.
However, it is the most common of the three and therefore the least valued. All US coins are now
copper alloys, and gun metals also contain copper.

Most copper is used in electrical equipment such as wiring and motors. This is because it
conducts both heat and electricity very well, and can be drawn into wires. It also has uses in
construction (for example roofing and plumbing), and industrial machinery (such as heat
exchangers).

Copper sulfate is used widely as an agricultural poison and as an algicide in water purification.

Copper compounds, such as Fehling’s solution, are used in chemical tests for sugar detection.

Natural abundance
Copper metal does occur naturally, but by far the greatest source is in minerals such as
chalcopyrite and bornite. Copper is obtained from these ores and minerals by smelting, leaching
and electrolysis. The major copper-producing countries are Chile, Peru and China.

Mineral: Bismuth (Bi)

Composition: Bismuth, usually with traces of arsenic, antimony, and sulfur
Color: Silver-white, sometimes with reddish hue. Oxidizes yellowish to dark gray.
Streak: Silver-white
Hardness: 2-2.5
Crystal System: HCP
Specific Gravity: 9.7-9.8
Luster: Metallic
Cleavage: Prismatic, Basal
Fracture: Hackly to uneven
Environment: In mesothermal veins, in hydrothermal replacement deposits, and in granite
pegmatites.
Rock type: Igneous, Metamorphic

Uses
Bismuth metal is brittle and so it is usually mixed with other metals to make it useful. Its alloys
with tin or cadmium have low melting points and are used in fire detectors and extinguishers,
electric fuses and solders.

Bismuth oxide is used as a yellow pigment for cosmetics and paints, while bismuth(III) chloride
oxide (BiClO) gives a pearly effect to cosmetics. Basic bismuth carbonate is taken in tablet or
liquid form for indigestion as ‘bismuth mixture’.

Natural abundance
Bismuth occurs as the native metal, and in ores such as bismuthinite and bismite. The major
commercial source of bismuth is as a by-product of refining lead, copper, tin, silver and gold
ores.

Mineral: Diamond (C)

Composition: Carbon
Color: Colorless, white, yellow, and brown, gray, and black. Colorless Diamonds are usually
lightly tinged with yellow, orange or brown. Rarely blue, green, red, orange, pink, or purple.
Streak: White
Hardness: 10
Crystal System: Isometric
Specific Gravity: 3.1 – 3.53
Luster: Adamantine. Rough stones have a greasy luster.
Cleavage: all sides - octahedral. Dodecahedral Diamonds, Borts, and Carbonado exhibit poor or
no cleavage.
Fracture: Conchoidal
Environment: Formed in plutonic rocks in the form of cylindrical plugs known as pipes, and
usually formed deep underground. Also occurs in alluvial placer deposits.
Rock type: Igneous, Sedimentary

Uses
In general, most people associate diamonds with jewelry, like rings or necklaces. However,
diamonds have many other uses too. In fact, only 20% of diamonds mined can actually be made
into jewelry. That leaves 80% of mined diamonds to be available for other uses. Here are some
of the most popular diamond uses besides jewelry:
 Man-made diamonds can be used in drill bits and other tools to help cut certain materials.
  Diamonds can be used to shape and polish other gemstones and for precision cutting or
engraining.
 Diamonds are used in windows that cover x-rays and other rays.
 Diamonds are used to conduct heat.
 Diamonds are used to coat microchips to conduct electricity.
 Diamonds are used in laboratory instruments.
Overall, diamonds are used in many instances, specifically involving cutting or intense
temperature changes because they are resistant and tough and do not create any friction. A saw
with diamond tips can actually cut through rock. Because they are so effective, diamonds will
continue to assist people in many ways, besides just shining brightly in a beautiful ring

Natural Occurrence and Processing

Diamonds are found in alluvial (loose earthy material deposited by running water) formations
and in volcanic pipes, filled for most of their length with blue ground or kimberlite, an igneous
rock consisting largely of serpentine. At the surface the blue ground is weathered to a clay called
yellow ground. Diamantiferous (or diamondiferous), or diamond-yielding, earth is mined both by
the open-pit method and by underground mining. After being removed to the surface, it is
crushed and then concentrated. Sorting is done by passing the concentrated material in a stream
of water over greased tables. The diamond, being largely water repellent, sticks to the grease, but
the other minerals retain a film of water, which prevents them from adhering to the grease. The
diamonds are then removed from the grease, cleaned, and graded for sale.

Mineral: Sulfur (S)

Composition: Sulfur
Color: Bright yellow to Yellow-brown
Streak: White
Hardness: 1.5-2.5
Crystal System: Orthorhombic
Specific Gravity: 2.0 – 2.1
Luster: Adamantine on clean, clear crystal surfaces; otherwise resinous or dull
Cleavage: 3,2
Fracture: Conchoidal
Environment: In sedimentary environments in evaporite and salt dome deposits, where it often
is a product of breakdown of sulfates caused by cetain bacteria. In volcanic deposits in hot
springs and fumaroles as a product of sublimation. Also occurs in igneous basalt rocks of recent
volcanic activity.
Rock type: Igneous, Sedimentary

Uses
Sulfur is used in the vulcanisation of black rubber, as a fungicide and in black gunpowder. Most
sulfur is, however, used in the production of sulfuric acid, which is perhaps the most important
chemical manufactured by western civilisations. The most important of sulfuric acid’s many uses
is in the manufacture of phosphoric acid, to make phosphates for fertilisers.

Mercaptans are a family of organosulfur compounds. Some are added to natural gas supplies
because of their distinctive smell, so that gas leaks can be detected easily. Others are used in
silver polish, and in the production of pesticides and herbicides.

Sulfites are used to bleach paper and as preservatives for many foodstuffs. Many surfactants and
detergents are sulfate derivatives. Calcium sulfate (gypsum) is mined on the scale of 100 million
tonnes each year for use in cement and plaster.

Natural abundance
Sulfur occurs naturally as the element, often in volcanic areas. This has traditionally been a
major source for human use. It is also widely found in many minerals including iron pyrites,
galena, gypsum and Epsom salts.

Elemental sulfur was once commercially recovered from wells by the Frasch process. This
involved forcing super-heated steam into the underground deposits to melt the sulfur, so it could
be pumped to the surface as a liquid.

Modern sulfur production is almost entirely from the various purification processes used to
remove sulfur from natural gas, oil and tar sands. All living things contain sulfur and when
fossilised (as in fossil fuels) the sulfur remains present. If unpurified fossil fuels are burnt, sulfur
dioxide can enter the atmosphere, leading to acid rain.

Mineral: Graphite (C)

Composition: Carbon
Color: Silver-grey to Black
Streak: Black
Hardness: 1-2
Crystal System: Hexagonal
Specific Gravity: 1.9-2.3
Luster: Metallic
Cleavage: Basal
Fracture: Conchoidal
Environment: Most often in metamorphic rock caused from the metamorphism of carbonates.
Rarely in pegmatites and hydrothermal veins.
Rock type: Igneous, Metamorphic

Uses
Graphite is found in a vast number of products and tools.
It is used in steel manufacturing and to coat the foundry molds of the metal industry.
It is the alloy component used in the manufacturing of tennis racket frames.
In the automobile industry, it is used in the manufacturing of brakes, brake linings, clutch
facings, engine parts, friction components and mechanical seals.
It is used in the manufacturing of anti-corrosive paints.
The high- tech industry has many uses for graphite, most notably in the lithium- ion batteries of
our laptops, small electronic devices, tools and electrical cars. It is also used in the
manufacturing of the simple alkaline battery.
Industrial lubricants, metal powders, polymer and rubber components all contain graphite.

Geologic Occurrence
Graphite is a mineral that forms when carbon is subjected to heat and pressure in Earth's crust
and in the upper mantle. Pressures in the range of 75,000 pounds per square inch and
temperatures in the range of 750 degrees Celsius are needed to produce graphite. These
correspond to the granulite metamorphic facies.

Mineral: Platinum (Pt)

Composition: Platinum, with small amounts of other elements such as iron, copper, nickel, gold,
or rare earth elements
Color: Tin-white, silver-gray, steel-gray, dark gray
Streak: Silver-gray. Streak is shiny.
Hardness: 4-4.5
Crystal System: Isometric
Specific Gravity: 14-19
Luster: Metallic
Cleavage: None
Fracture: Hackly
Environment: Most often in placer deposits. The primary occurrence is in plutonic rocks such
as Olivine.
Rock type: Igneous, Sedimentary

Uses
Platinum is used extensively for jewelry. Its main use, however, is in catalytic converters for
cars, trucks and buses. This accounts for about 50% of demand each year. Platinum is very
effective at converting emissions from the vehicle’s engine into less harmful waste products.

Platinum is used in the chemicals industry as a catalyst for the production of nitric acid, silicone
and benzene. It is also used as a catalyst to improve the efficiency of fuel cells.

The electronics industry uses platinum for computer hard disks and thermocouples.
Platinum is also used to make optical fibres and LCDs, turbine blades, spark plugs, pacemakers
and dental fillings.

Platinum in the environment

Platinum primary occurrence is with other metal ores associated with basic igneous rocks.
Platinum nuggets occur naturally as the uncombined metal, as does an alloy of platinum- iridium.
Three-quarters of the world's platinum comes from South Africa, where it occurs as cooperite,
while Russia is the second largest produced, followed by North America. World production of
platinum is around 155 tonnes a year and reserves total more than 30.000 tonne.

Mineral: Silver (Ag)

Composition: Silver, sometimes mixed with gold, mercury, arsenic, and antimony
Color: Silver-white on untarnished surfaces. Tarnishes dark yellow to black.
Streak: Silver-white to light gray. Streak shiny.
Hardness: 2.5 -3
Crystal System: Isometric
Specific Gravity: 9.6-12
Luster: Metallic
Cleavage: None
Fracture: Hackly
Environment: In volcanic basalt rocks and in hydrothermal veins and mesothermal veins. May
also be formed by the breakdown of sulfur from lead or zinc deposits.
Rock type: Igneous, Metamorphic

Uses
Sterling silver contains 92.5% silver. The rest is copper or some other metal. It is used for
jewellery and silver tableware, where appearance is important.

Silver is used to make mirrors, as it is the best reflector of visible light known, although it does
tarnish with time. It is also used in dental alloys, solder and brazing alloys, electrical contacts
and batteries. Silver paints are used for making printed circuits.

Silver bromide and iodide were important in the history of photography, because of their
sensitivity to light. Even with the rise of digital photography, silver salts are still important in
producing high-quality images and protecting against illegal copying. Light-sensitive glass (such
as photochromic lenses) works on similar principles. It darkens in bright sunlight and becomes
transparent in low sunlight.

Silver has antibacterial properties and silver nanoparticles are used in clothing to prevent bacteria
from digesting sweat and forming unpleasant odours. Silver threads are woven into the fingertips
of gloves so that they can be used with touchscreen phones.
Mineral: Iron (Fe)
Composition: Iron
Color: Steel-gray to black
Streak: Steel-gray. Streak shiny.
Hardness: 4-5
Crystal System: Isometric
Specific Gravity: 7.9-8.9
Luster: Metallic
Cleavage: None
Fracture: Hackly
Environment: Most often in meteorites or meteorite impact sites and craters. In terrestrial
environments in volcanic basalt formed by reduction of iron oxides in contact with carbonates.
Rock type: Igneous, Meteoric

Uses
Iron is an enigma – it rusts easily, yet it is the most important of all metals. 90% of all metal that
is refined today is iron.

Most is used to manufacture steel, used in civil engineering (reinforced concrete, girders etc) and
in manufacturing.

There are many different types of steel with different properties and uses. Ordinary carbon steel
is an alloy of iron with carbon (from 0.1% for mild steel up to 2% for high carbon steels), with
small amounts of other elements.

Alloy steels are carbon steels with other additives such as nickel, chromium, vanadium, tungsten
and manganese. These are stronger and tougher than carbon steels and have a huge variety of
applications including bridges, electricity pylons, bicycle chains, cutting tools and rifle barrels.

Stainless steel is very resistant to corrosion. It contains at least 10.5% chromium. Other metals
such as nickel, molybdenum, titanium and copper are added to enhance its strength and
workability. It is used in architecture, bearings, cutlery, surgical instruments and jewellery.

Cast iron contains 3–5% carbon. It is used for pipes, valves and pumps. It is not as tough as steel
but it is cheaper. Magnets can be made of iron and its alloys and compounds.

Iron catalysts are used in the Haber process for producing ammonia, a nd in the Fischer–Tropsch
process for converting syngas (hydrogen and carbon monoxide) into liquid fuels

Natural abundance
Iron is the fourth most abundant element, by mass, in the Earth’s crust. The core of the Earth is
thought to be largely composed of iron with nickel and sulfur.

The most common iron-containing ore is hematite, but iron is found widely distributed in other
minerals such as magnetite and taconite.
Commercially, iron is produced in a blast furnace by heating hematite or magnetite with coke
(carbon) and limestone (calcium carbonate). This forms pig iron, which contains about 3%
carbon and other impurities, but is used to make steel. Around 1.3 billion tons of crude steel are
produced worldwide each year.
 SULFIDES
The minerals that make up the sulfide class are composed of one or more metals
combined with sulfur. They form an important group of minerals which includes the majority of
the ore minerals for iron, copper, nickel, lead, cobalt, zinc, and silver. They are also the ore
minerals of most metals used by industries.Most of the sulfides are simple structurally, exhibit
high symmetry in their crystal forms, and have many of the properties of metals, including
metallic lustre and electrical conductivity. They ofte n are strikingly coloured and have a low
hardness and a high specific gravity.

Argentite (Ag2S or silver sulfide)

The name refers to the high- temperature form of silver sulfide, only stable over 177° C.
The mineral acanthite is the stable form of this mineral below 177° C. This is the tarnish that
forms on sterling silver. An important ore of silver, it is found in moderately low-temperature
hydrothermal sulfide veins and in zones of secondary enrichment. Its name comes from the Latin
"argentum" meaning “silver.”

Physical Properties
Color: blackish lead-gray
Streak Color: Lead gray
Transparency: Opaque
Tenacity:
Luster: metallic
Hardness: 2-2.5
Specific Gravity: 7.2-7.4
Density: 7.3
Magnetism: Nonmagnetic
Habbit: cubic or octahedral crystals, often in groups; arborescent or hairlike massive
fracture: subconchoidal fracture
Cleavage: None
Crystal system: isometric

Diagnostic features
Low hardness and the ease with which it is scratched

Occurrence: Low temperature hydrothermal

Uses: Major ore of silver

Arsenopyrite (FeAsS or Iron Arsenic Sulfide)

 This is the most common mineral containing arsenic and is the principal source of
arsenic. It occurs in high temperature gold-quartz or tin hydrothermal veins, pegmatites, and
metamorphic rocks. Its name is a contraction of the older term: arsenical pyrite.

Physical properties
Crystal System: Monoclinic
Crystal Form: colummar
Habit:Plates or botryoidal form
Hardness:5.5-6.0
Cleavage/Fracture:{001}cleavage: distinct, uneven.
Luster:Metallic
Color: Silver white to steel gray
Steak:Grayish black
Specific Gravity:6-6.2
Other Characteristics:
(1) Opaque
(2) Spear-shaped twins with grooved faces are common.
(3) After heating, it releases the strong garlic smell.

Chemical Properties
Formula: FeAsS
Class: Sulfides
Characteristics: Soluble to nitric acid

Diagnostic Features
(1) Silver white to steel gray color
(2) High hardness
(3) After striking or heating, it will release the smell of garlic.

Occurrence
Common in many different environment. In magmatic sulphide ores in pegmatic and
hydrothermal veins and in metamorph rocks

Uses
Important ore of arsenic, minor source of gold and as mineral specimens

Bornite (Cu5FeS4 or Copper Iron Sulfide)

Known as the "peacock ore" due to it quickly tarnishing to an iridescent purple after
exposure to air and moisture, this mineral has been known since 1725, but was not given its
current name until 1845 when it was named for Ignaz von Born (1742-1791), an Austrian
mineralogist. A widely occurring copper ore, it is usually found associated with other copper
minerals in hypogene deposits.
Physical Properties
Crystal System: Axis of symmetry
Crystal Form: Cube, octahedron or dodecahedron
Hardness: 3
Cleavage/Fracture: None, uneven
Luster: Metallic
Color: Reddish bronze Streak: Grayish black
Specific Gravity: 4.9-5.3
Other Characteristics:
(1)Brittle
(2)Good conductivity
(3)Surface tarnishes to iridescent deep blue, purple and red.

Chemical Properties
Formula: Cu5FeS4
Class: Sulfide
Characteristics: Soluble to nitric acid

Occurrences
Common and widespread in copper ore deposits. It also occurs in basic intrusives, in dikes,
in contact metamorphic deposits, in quartz veins and in pegmatites.

Diagnostic Features
(1)Reddish bronze color
(2)Grayish black streak
(3)Surface readily tarnishes to iridescent deep blue, purple, or red color
(4)Low hardness

Uses
Used for refining copper

Chalcocite (Cu2S or Copper Sulfide)

Once of the most important copper-ore minerals, chalcocite occurs as a secondary
mineral in or near the oxidized zone of copper sulfide deposits. Under surface conditions, the
primary copper sulfides are oxidized, the soluble sulfates formed move downward reacting to
form chalcocite, and thus, enriching the ore in copper. The water table is the lower limit of the
zone of oxidation and here a "chalcocite blanket" may form.
Physical properties
Lustre: Metallic
Color: Blue black, gray, black, black gray, or steel gray
Streak: Blackish lead gray
Hardness (Mohs):2½ - 3
Tenacity: Brittle
Cleavage: Poor/Indistinct; Indistinct on (110)
Fracture: Conchoidal
Density: 5.5 - 5.8 g/cm3 (Measured)
Crystal System: monoclinic

Occurrence
Formed in copper deposits, usually as a secondary mineral in the oxidized zone, and often
as an alteration of primary copper minerals in ore veins. Also found in volcanic basalt deposits.

Diagnostic feature
color, soft, sooty appearance

Chemical properties
Formula:Cu2S

Uses
Used as an ore of copper

Chalcopyrite
A major ore of copper, chalcopyrite is the most abundant of the copper-bearing minerals.
It is a primary mineral in hydrothermal veins and the principal copper mineral of porphyry-
copper deposits. This mineral is easily recognized by its brass-yellow color and greenish-black
streak. Its name is derived from the Greek word meaning "copper" and from "pyrites" meaning
“strike fire.”

Physical Properties
Crystal System: Cube
Crystal Form: Tetrahedron or Octahedron
Hardness:3.5-4
Cleavage/Fracture:{011}Cleavage: perfect, uneven to shell-shape
Luster:Metallic
Color:Brass yellowStreak:Green and black
Specific Gravity:4.1-4.3
Other Characteristics:
 1)Conductive
(2)Wedge-shaped, usually crystal twins, with uneven face and may be grooved.
(3)Opaque
(4)Bright metallic with iridescent tarnished luster.

Chemical Properties
Formula:CuFeS2
Characteristics:
(1)Soluble to nitric acid
(2)When flaming, the fire has green color.

Occurences
(1)Ultrabasic mineral, found most frequently with pyrrhotite and Pentlandite.
(2)Developing in speck copper mineral, associated with Molybdenite.
(3)Occurring in hydrothermal deposit, associated with galena, Sphalerite and pyrite.
(4)Distributing in sedimentary copper deposits, associated with Molybdenite.

Diagnostic Features
It is easy to confuse between chalcopyrite and pyrite. Chalcopyrite is more yellowish,
softer with the streak of black with green color.

Uses
An important copper ore.

Cinnabar
This mineral is easily recognized by its red color and scarlet streak, high specific gravity,
and cleavage. It is a low temperature hydrothermal mineral and the only important source of
mercury. The name is from the Persian possibly meaning "dragon's blood."

Physical Properties
Crystal System: hexagonal
Crystal Form: rhombohedral or plates
Habit: Granular or tabular form
Hardness:2-2.5
Cleavage/Fracture: Prismatic, {10_10}
cleavage:perfect
Luster: Metallic
Color: Fresh red
Streak: Fresh red
Specific Gravity:8.0-8.2
 Other Characteristics:
(1) Translucent
(2)Optical rotator
(3)Poor conductor of electricity
(4)Spearhead crystal twin

Chemical Properties
Formula:HgS
Characteristics: Containing impunities of iron oxide or clay.

Occurences
Occurring in low hydrothermal veins, associated with pyrite, calcite, stibnite, and realgar.

Diagnostic Features
(1)Fresh red color and streak
(2)High specific gravity
(3)Low hardness

Major Uses
Used for refining mercury.

Covellite
Discovered in 1832 and named after Niccolo Covelli (1790-1829), an Italian mineralogist
and discoverer of the mineral at Mount Vesuvius, this mineral is characterized by its indigo-blue
color. It is usually found as a secondary copper mineral in copper deposits and rarely
occasionally as a volcanic sublimate.

Physical Properties
Crystal System: Hexagonal
Crystal Form: (Hexagonal) Platy
Habit: Foliated, shell-like
Hardness: 1.5-2
Cleavage / Fracture: {0001} perfect
Luster: Submetallic
Color: Indigo blue
Streak: Lead gray to black
Specific Gravity: 4.6-4.8
Other Characteristics:
(1)Opaque
(2)Producing blue flames when burned.
 (3)Often tinged with purple iridescence.

Chemical Properties
Formula: CuS
Characteristics: Soluble in hydrochloric acid.

Occurences
It occurs in the parts of copper veins that have been altered, due to fluids seeping through
the vein.

Diagnostic Features
(1)Indigo blue, often tinged with purple iridescence.(2)The thin cleavage sheets that may
form on covellite, due to its perfect cleavage, are flexible.

Major Uses
An ore of copper, but not abundant.

Galena
It is a very common sulfide that has been worked for its lead content as early as 3000 BC.
The name is derived from the Latin galena, a name originally given to lead ore.

Physical Properties
Crystal System: Isometric
Crystal Form: Cubic, octahedral
Habit: Massive, granular, skeletal, stalactite
Hardness: 2.5
Cleavage / Fracture: Cubic, {100} perfect
Luster: Metallic
Color: Lead gray
Streak: Lead gray
Specific Gravity: 7.4-7.6
Other Characteristics:
(1)With a weak electric conductivity
(2)Opaque
(3)Sometimes, cubic or octahedral aggregates formed.

Chemical Properties
Formula: PbS
Characteristics:
 (1)Galena is not stable when exposed to air and may be altered to minerals, such as
Anglesite and white lead.
(2)Soluble in hydrochloric and nitric acids.

Occurences
Often found in a variety of hydrothermal environments and, in particular, in the low to
medium temperature deposits, Galena is usually associated with sphalerite, pyrite, fluorite,
calcite, chalcopyrite and quartz. It is also found in metasomatic deposits.

Diagnostic Features
(1)Great specific gravity
(2)Cubic cleavage
(3)Lead gray
(4)Metallic luster

Major Uses
(1) One of the major sources of lead
(2) Galena usually consists of silver, so it could be a source of silver if the amount is
abundant.

Greenockite
Discovered in 1840, this mineral was named for Lord Greenock (1783-1859). It is the
most common mineral containing cadmium, but it is found only in a few localities and in small
amounts, usually as an earth-coating on zinc ores, especially sphalerite. Cadmium is used in
alloys for antifriction bearings, low-melting alloys, and in electroplating.

Physical properties
Lustre:Adamantine, Resinous
Colour: Yellow to red.
Streak: Orange-yellow to brick red.
Hardness: 3 - 3½
Cleavage: Distinct/Good
Distinct on {1122}, imperfect on {0001}.
Fracture: Conchoidal
Density: 4.8 - 4.9 g/cm3 (Measured)
Crystal System: Hexagonal

Chemical Properties
Formula: CdS
Characteristics: Soluble in contact with hydrochloride
Occurences
It usually covers sphalerite as a layer of dirt.

Diagnostic Features
(1)Yellow, orange, or deep red in color
(2)Ranging from orange yellow to brick red in streak
(3)Paragenetic with zinc ores, especially with sphalerite
(4)Soluble in hydrochloride

Major Uses
Greenockite is a source of cadmium, which is often used in electroplating. Cadmium
alloy can be the material for manufacturing high-speed bearing. Cadmium sulfide could be a
yellow pigment.

Marcasite
Characterized by its cockscomb form, this mineral was named in 1845 after an Arabic or
Moorish name applied to pyrite and similar metallic bronze-colored minerals. It is frequently
found replacing organic matter, forming fossils, and in sedimentary beds, particularly coal beds.

Physical Properties
Crystal System: Orthorhombic
Crystal Form: Tabular; prismatic
Habit: Concretion; conchoidal; cockscomb; massive; granular
Hardness: 6-6.5
Cleavage/Fracture: {101} clear; uneven fracture
Luster: Metallic
Color: Light brass-yellow
Streak: gray to green
Specific Gravity: 4.8-4.9
Other Characteristics:
(1) Crisp
(2) Opaque
(3) Turning to magnetic spheres after melted

Chemical Properties
Formula: FeS2
Characteristics:
(1) Marcasite is unstable and prone to turn into pyrite
(2) It is easy for marcasite to dissolve in air.
(3) Soluble in nitric acid.
Diagnostic Features
Light brass-yellow (even lighter than pyrite).

Occurrences
Most frequently found in sedimentary rocks and coal beds, as a replacement mineral
forming fossils, it is a mineral of low-temperature, near-surface, environments, forming from
acid solutions. Pyrite, the more stable form of FeS^2, forms under conditions of higher
temperatures and lower acidity or alkaline environments.

Major Uses
Marcasite produces sulfuric acid.

Millerite
Named in 1845 in honor of the English mineralogist ( ) William Miller (1801-1880) ( )
who first studied the crystals, this mineral forms as a low-temperature mineral often in cavities
and as an alteration of other nickel minerals. It is commonly found as radiating and jack-straw
clusters of shiny metallic acicular crystals, pale brass-yellow with an iridescent tarnish.

Physical Properties
Crystal System: Trigonal
Lustre: Metallic
Colour: Pale brass-yellow, with an iridescent tarnish, and greenish-grey.
Streak: Greenish black.
Hardness (Mohs): 3 - 3½
Cleavage: Perfect; Perfect on {1011} and {0112}.
Fracture: Irregular/Uneven
Density: 5.5
Magnetism: Magnetic after heating

Chemical Composition
Formula: NiS

Occurrence
A low-temperature mineral which occurs in sulfidic limestones and dolostones, and as a
late-forming mineral in nickel sulfide deposits.

Major Uses
Mineral specimens and as a very minor ore of nickel.
Molybdenite
The principal ore of molybdenum, this mineral was named from the Greek word meaning
"lead." Currently, this mineral is being researched as a possible replacement semiconductor for
silicon transistors in electronic chips. It forms as an accessory mineral in granites and is
commonly found in high temperature vein deposits and contact metamorphism.

Physical Properties
Crystal System: Hexagonal
Crystal Form: Tabular; prismatic
Habit: Scaly
Hardness: 1-1.5
Cleavage/Fracture: {0001} perfect
Luster: Metallic
Color: Lead gray
Streak: Grayish black
Specific Gravity: 4.62-4.73
Other Characteristics:
(1) Veins on the underside of the crystal
(2)Opaque
(3)Smooth
(4)Bendable (thin sections)

Chemical Properties
Formula: MoS2
Characteristics: Primarily molybdenum and sulfur; sulfur dioxide is released after heated.

Diagnostic Features
(1) Lead gray
(2) Low hardness
(3) Perfect cleavage

Occurences
(1) Molybdenite is mainly formed in low hydrothermal systems of acid rocks, frequently
along with small amounts of pyrites.
(2) Partly created in contact- metasomatism and often associated with brass, pyrite, quartz,
and scheelite.

Major Uses
Molybdenite is the major source of molybdenum and rhenium, which are used in the
production of special steels, electronics and chemicals.
Niccolite
This mineral was named from the German nickname for the ore miners called
"kupfernickel' (copper nickel); after Old Nick and his mischievous gnomes, because the ore
seemed to contain copper but yielded none. It is, however, a minor ore of nickel.

Physical Properties
Crystal System: Hexagonal
Lustre: Metallic
Colour: Pale copper red
Cleavage: {1010} Imperfect, {0001} Imperfect
Streak: Pale Brownish black
Hardness (Mohs): 5 - 5½
Fracture: Conchoidal
Density:7.78-7.8 Average = 7.79
Magnetism: Nonmagnetic

Chemical Composition
Formula: NiAs

Occurrence
In ore veins with silver, copper, and nickel arsenides and sulfides.

Major Uses
As a minor ore of nickel and as mineral specimens.

Orpiment
A rare mineral usually associated with realgar, orpiment is characterized by its yellow
color. It was formerly used as pigment, but discontinued due to its arsenic content. Its name
comes from the Latin auripigmentum meaning "golden paint," in allusion to its color and
because the substance was supposed to contain gold.

Physical Properties
Crystal System: Monoclinic
Crystal Form: Prismatic (rare)
Habit: Massive; prismatic
Hardness: 1.5-2
Cleavage/Fracture: {010} perfect; uneven fractureLuster: Pearly
Color: Lemon and brown
Streak: Light yellow
Specific Gravity: 3.4-3.5
Other Characteristics: Fusible, strong garlic smell after heated due to arsenic
Chemical Properties
Formula: As2S3
Characteristics: Soluble in nitric acid

Diagnostic Features
(1) Lemon and brown-yellow color
(2) Light yellow streaks
(3) Perfect cleavage on {010}

Occurences
Found in low hydrothermal mineral deposit and sometimes around hot springs. Frequent
paragenesis with realgar and stibnite.

Major Uses
Same as Realgar, when mixed with saltpeter (potassium nitrate), orpiment can be used to
produce fireworks; when mixed with potassium and lime, it is used as depilatory.

Pentlandite
Discovered in 1856, this mineral was named after J. B. Pentland who discovered the
mineral at Sudbury, Ontario. It is the principal ore of nickel, which is used chiefly in steel.
Nickel is also an essential constituent of stainless steel. The mineral is usually found intergrown
with pyrrhotite, from which it can be distinguished from because it is non-magnetic.

Physical Properties
Crystal System: Isometric
Luster: Metallic
Colour: Bronze or brown
Streak: Light bronze-brown
Hardness (Mohs): 3½ - 4
Parting: On {111}
Fracture: Conchoidal
Cleavage: None
Density: 4.6 – 5 Average=4.8
Magnetism: Nonmagnetic

Chemical Composition
Formula: (Fe,Ni)9S8

Occurrence
Massive sulfide in ultramafic rocks.
Major Uses
As the principle ore of nickel, a minor ore of iron and as mineral specimens.

Pyrite
Nicknamed "Fool's Gold" for people frequently mistaking it for gold, pyrite is the most
common sulfide mineral and is found in a wide variety of geological formations. It is often
mined for the gold or copper associated with it and is a source of sulfur for sulfuric acid. The
name is from a Greek word meaning "fire" for the sparks that flew from it when hit with another
mineral or metal.

Physical Properties
Crystal System: Isometric
Crystal Form: Cubic; dodecahedral; octahedral
Habit: Massive; granular; reniform; concretion; botryoidal; discoid
Hardness: 6-6.5
Cleavage/Fracture: {001} obscure; conchoidal to uneven fractureLuster: Metallic
Color: Copper-yellow
Streak: Black to green black
Specific Gravity: 4.9-5.2
Other Characteristics:
(1) On the cubic crystal planes, lines are frequent, and the streaks on two
connected planes are perpendicular.
(2) With metallic luster, which dims if the mineral is placed in air for a long time
(3) Interpenetrant crysta, or so-called Iron Cross Twin.
(4) Crisp
(5) Opaque
(6) Occasionally slightly magnetic

Chemical Properties
Formula: FeS2
Characteristics:
(1) In oxidative environment, pyrite often decomposes into sulfate (such as
jarosite) and hydrate (such as goethite), which form iron.
(2) After oxidation and hydrolysis, pyrite splits into vitiol and sulfate that make
underground water acid.
(3) Slightly dissolvable in nitric acid.

Diagnostic Features
(1) Copper-yellow
(2) Black streaks
 (3) Lines on the crystal planes
(4) High hardness

Occurences
Pyrite is the most widely spread sulfide. It can be found in all kinds of rocks, and also
exists in coal beds.
(1) A lot of pyrite would gather in hydrothermal environment along with galena,
sphalerite, pyrrhotite, arsenopyrite.
(2) Usually in the forms of concretion or compact massive crystals in sedimentary rocks
and coal beds.

Major Uses
Raw material of vitriol

Pyrrhotite
Found with pentlandite in basic igneous rocks, veins, and metamorphic rocks, this
mineral is mined for its associated nickel, copper, and platinum. It is recognized by its massive
nature, bronze color, and magnetism. The name comes from the Greek word meaning "reddish."

Physical Properties
Crystal System: Hexagonal
Crystal Form: False hexagonal
Habit: Massive; granular
Hardness: 4
Cleavage/Fracture: no cleavage; sub-conchoidal to uneven
Luster: Metallic
Color: Dark blue and copper-yellow
Streak: Grayish black
Specific Gravity: 4.58-4.65
Other Characteristics:
(1) Crisp
(2) Highly conductive
(3) Magnetic
(4) Dark, brownish metallic rusty color on the surface

Chemical Properties
Formula: Fe1-xS
Characteristics: Sasy to dissolve, oxidize, and hydrate into iron hydroxide (Fe(OH)3) in
oxidative environment.

Diagnostic Features
 (1) Dark brass-yellow
(2) Magnetic
(3) Grayish black streaks

Occurences
(1) When found in ultrabasic rocks or basic rocks of cupriferous sulfide and nickelic
sulfide, pyrrhotite is frequently in paragenesis with chalcopyrite and pantlandite.
(2) When found in hydrothermal mineral deposit, pyrrhotite is frequently in paragenesis
with sphalerite, galena and chalcopyrite.
(3) When found in contact- metasomatiic deposit, pyrrhotite is often in paragenesis with
pyrite, magnetite, and chalcopyrite.

Major Uses
Raw material of vitriol

Realgar
This mineral is distinguished by its red color, resinous luster, orange-red streak, and its
association with orpiment. On long exposure to light, it disintegrates to a reddish- yellow powder.
It is found in veins of lead, silver and gold ores, and as a deposit from hot springs. It is used as a
pigment. The name is derived from the Arabic Rahj al ghar meaning "powder of the mine."

Physical Properties
Crystal System: Monoclinic
Crystal Form: Columnar or acicular
Habit: Granular or massive
Hardness: 1.5-2
Cleavage / Fracture: {010} perfect cleavage ;{101};{100};{120}
Indistinct Fracture: Conchoidal
Luster: Adamantine
Color: Red or orange-red
Streak: Light orange to red
Specific Gravity: 3.48
Other Characteristics:
(1) Transparent to translucent
(2) Striated surface
(3) Strong garlic smell when heated
(4) Resinous luster at the facture

Chemical Properties
Formula: AsS
Characteristics:
 (1) Long exposure to light will cause a photochemical reaction which will deteriorate
realgar into brownish yellow powder of orpiment.
(2) Partially dissolvable in acids and KOH solutions.

Diagnostic Features
Realgar can be easily mistaken for cinnabar. However, realgar has a smaller specific
gravity and light orange to orange-red streaks while cinnabar has more reddish streaks.

Occurences
(1) Mostly occurs in low hydrothermal veins; often intergrown with cinnabar, stibnite and
orpiment.
(2) Often found in hot spring deposits and as volcanic sublimate products, often
intergrown with orpiment.

Major Uses
(1) An Ore of arsenic
(2) Also used in Chinese medicine. However, with 70% of arsenic, realgar might be toxic
when overdosed.

Skutterudite
Discovered in 1845 and named after its discovery locality in Skuterud Mines, Norway,
this mineral forms in moderate to high temperature hydrothermal veins. It is an ore of cobalt and
nickel. Cobalt is chiefly used in alloys for making permanent magnets and high-speed tool steel.

Physical Properties
Crystal System: Isometric
Lustre: Metallic
Colour: Tin-white to silver-gray, gray (tarnished)
Streak: Black
Hardness (Mohs): 5½ - 6
Cleavage: Distinct/Good (Distinct on {001}{111} in traces on {011})
Fracture: Irregular/Uneven, Conchoidal
Density: 6.5 g/cm3 (Measured)
6.821 g/cm3 (Calculated)
Magnetism: Nonmagnetic

Chemical Composition
Formula: (Co,Ni)As3-x

Occurrence
Hydrothermal ore mineral found in high temperature veins with other Ni-Co minerals.
Major Uses
A minor ore of Cobalt and Nickel

Sphalerite
This mineral can be recognized by its striking resinous luster and perfect cleavage. The
red variety is called "ruby blende" or "ruby zinc," while the dark varieties are known as "black
jack." It is the most important ore of zinc, which is used in galvanizing iron, making brass paint,
wood preservative, and in dyes and medicine. The name comes from the Greek word meaning
"treacherous," an allusion to the ease with which dark varieties were mistaken for galena, but
yielded no lead.

Physical Properties
Crystal System: Isometric
Cleavage: {110} Perfect, {110} Perfect, {110} Perfect
Color: Brown, Yellow, Red, Green, Black.
Density: 3.9 - 4.2, Average = 4.05
Fracture: Uneven
Hardness: 3.5-4 - Copper Penny-Fluorite
Luster: Resinous - Greasy
Streak: brownish white

Chemical Composition
Formula: (Zn,Fe)S

Occurrence
Sphalerite are found where hydrothermal activity or contact metamorphism has brought
hot, acidic, zinc-bearing fluids in contact with carbonate rocks. There, sphalerite can be
deposited in veins, fractures, and cavities, or it can form as mineralizations or replacements of its
host rocks.

Major Uses
The primary ore of zinc. Often mined for minor amounts of indium, cadmium,
germanium, or gallium as profitable byproducts. Mineral specimens. Faceted stones for
collectors.

Stibnite
Found in low-temperatures hydrothermal veins or replacement deposits and in hot spring
deposits, this mineral is characterized by its bladed crystals and lead-gray color. The name
reflects its antimony content. The Greek name for the mineral was "stibi" from whence came
Latin stibium and the old name for the element antimony (Sb).
Physical Properties
Crystal System: Orthorhombic
Crystal Form: Columnar or acicular
Habit: Radiating or massive
Hardness: 2
Cleavage/Fracture: {010} perfect cleavage;
Fracture: Conchoidal
Luster: Metallic
Color: Lead gray
Streak: Lead gray
Specific Gravity: 4.52-4.62
Magnetism: Nonmagnetic
Other Characteristics:
(1) Distinct lengthwise striations on the crystal surface
(2) Opaque

Chemical Properties
Formula: Sb2S3
Characteristics: Dissolvable in heated hydrochloric acid or nitric acid

Occurences
(1) Mostly found in low-temperature hydrothermal veins, often intergrown with fluorite,
calcite, realgar, orpiment, quartz and cinnabar.
(2) Occasionally found in hot spring deposits.

Diagnostic Features
(1) Lead gray color
(2) Columnar crystals, often striated
(3) When applied with KOH solution, the crystal surface will turn yellow and then
orange-red.

Major Uses
A major ore of antimony, which can be used to produce alloys, fireworks, plastic, glass
and textile.
 SULFOSALTS
Sulfosalt, also spelled sulphosalt, any of an extensive group of minerals, mostly rare
species, marked by some of the most complicated atomic and crystal structures known to
inorganic chemistry. They conform to the general composition AmBnXp, in which m, n,and p are
integers; A may be lead, silver, thallium, or copper; B may be antimony, arsenic, bismuth, tin, or
germanium; and X may be sulfur or selenium. Formerly it was believed that the sulfosalts were
salts of complex hypothetical thioantimonic or thioarsenic acids (e.g., HSbS2 , H18 As4 S15 ,
H3 AsS3 ), but X-ray diffraction analyses indicate that the atomic structures of many sulfosalts are
based on structural fragments of simpler compounds such as galena (lead sulfide; PbS) blocks
and stibnite (antimony trisulfide; Sb2 S3 ) sheets. No encompassing theory has been evolved to
rationalize many of these curious compounds. The complexity of many of the structures
evidently results from their having crystallized at low temperatures and the consequent high
degree of ordering of the metal atoms. Syntheses of such compositions at higher temperature
usually result in structures simpler than the complicated low-temperature forms.

1. ENARGITE
Consisting of copper, arsenic and sulfur and small amounts of iron and zinc may be present.
Enargite may contain some antimony in place of the arsenic. Enargite is usually found in prismatic
crystals and are typically striated lengthwise. With a metallic luster, Enargite is notable for its grayish
black color and streak, it is distinguished by its cleavage. However, a tarnish will dull the luster of the
crystals and the black color may turn into silver white over time if exposed to sun or air. An ore of
copper, Enargite can also be a source of arsenic oxide. Discovered in 1850, its name comes from the
Greek meaning "distinct," in allusion to the cleavage.

Physical Properties
Crystal System: Orthorhombic
Crystal Form: Prismatic, tabular
Hardness: 3
Cleavage: {110} perfect, {100} and {010} distinct
Luster: Metallic
Color: Grayish black to steel gray
Streak: Black to dark gray
Specific Gravity: 4.4-4.5
Fracture: Irregular/Uneven
Magnetism: Nonmagnetic
Other Characteristics:
(1) Crystals typically striated lengthwise.
(2) Opaque
(3) Emitting an odor of garlic when heated.

Chemical Properties
Formula: Cu3AsS4
Class: Sulfosalts
 Characteristics: Soluble in nitric acid

Diagnostic Features
(1) Grayish black to steel gray
(2) Crystals are typically striated lengthwise.
(3) An odor of garlic is emitted when heated.

Occurences
Enargite is usually found in hydrothermal and metasomatic deposits and is often associated with
quartz, galena, luzonite, bornite, sphalerite, pyrite and chalcopyrite.

Major Uses
An ore of copper as well as a source of arsenic oxide.

2. JAMESONITE
Jamesonite consists mainly of lead, iron, antimony, and sulfur. It sometimes contains minor amounts of
copper and zinc. As a result of its acicular, fibrous, or plumose (feather-like) crystal habit, it has been
called feather ore. Its important features include its metallic luster, lead-gray color and streak, as well as
its acicular fibrous or plumose crystal habit. Jamesonite, from which lead can be extracted, is mainly
formed in medium-low temperature hydrothermal veins. Discovered in 1825 in Cornwall, England, this
mineral is named for mineralogist Robert Jameson (1774-1854) of Edinburgh. It is recognized by its
characteristic fibrous appearance and is found in ore veins of low to moderate temperatures.

Physical Properties
Crystal System: Monoclinic
Crystal Form: Acicular, fibrous
Crystal Habit: Massive, plumose
Hardness: 2.5
Cleavage/Fracture: {001} good; uneven or shell-like fractures
Luster: Metallic
Color: Lead-gray
Streak: Lead-gray
Specific Gravity: 5.5-5.7
Magnetism: Nonmagnetic
Other Characteristics: Opaque

Chemical Properties
Formula: Pb4 FeSb6 S14

Diagnostic Features
(1) Fibrous or acicular crystal habit
(2) It can be told apart from stibnite by means of the absence of parallel crystal axes in cleavage.

Occurrence
 Late stage hydrothermal mineral formed at moderate to low temperature.

Major Uses
A minor source of lead.

3. TENNANTITE
Commonly found in hydrothermal veins formed at low to moderate temperatures, this mineral
was named after Smithson Tennant (1761-1815), an English chemist. It was discovered in 1819 at
Cornwall, England.

Physical Properties of Tennantite

Crystal System: Isometric
Crystal Habit: Massive, Granular
Cleavage: None
Color: Steel gray, Black.
Density: 4.6 - 4.7, Average = 4.65
Fracture: Hackly, Subconchoidal
Hardness: 3.5-4 - Copper Penny-Fluorite
Luster: Metallic
Magnetism: Nonmagnetic
Streak: reddish gray
Specific Gravity: 4.6-4.8
Other Characteristics: Opaque

Chemical Properties
Formula: Cu6 [Cu4 (Fe,Zn)2 ]As4 S13

Occurrence
Commonly found in hydrothermal veins formed at low to moderate temperatures.

Major uses
Used as minor ore of silver.

4. TETRAHEDRITE
Mainly composed of copper, antimony and sulphur, tetrahedrite often contains iron, zinc and occasionally
small amounts of silver, lead and mercury. It shares the same crystal structure with tennantite (Tennantite,
Cu12As4S13). Both belong to a solid solution series. Antimony-rich specimens are tetrahedrite while
arsenic-rich ones are tennatite.
Tetrahedrite is characterized in its metallic luster, gray to black colors and britt leness. It is one of the
most common sulfosalts, often formed in low-temperature to mid-temperature hydrothermal veins.
Tetrahedrite is used as an ore of copper and silver. The name is derived from the common tetrahedral
form of its crystals.

Physical Properties
 Crystal System: Isometric
Crystal Form: Tetrahedron
Hardness: 3-4.5
Cleavage/Fracture: No cleavages; fracture: Subconchoidal to uneven
Luster: Metallic
Color: Gray to black
Streak: Brown to black
Specific Gravity: 4.6-5.1
Other Characteristics:
(1) Crystal twinning
(2) Opaque

Chemical Properties
Formula: (Cu,Fe)2Sb4S13
Class: Sulfides
Chemical PropertiesDissolvable in nitric acid

Diagnostic Features
(1) Tetrahedron crystals
(2) Grayish black color
(3) Metallic luster

Occurences
Mostly found in hydrothermal veins, often intergrown with fluorite, barite, quartz, sphalerite,
pyrite and galena.

Major Uses
An ore of copper and sliver

5. Argyrodite
Argyrodite is a rare silver germanium sulfide mineral. It was first discovered in the silver mining
area of Freiberg, Saxony, Germany in the Himmelsfurst Mine. When it was discovered, the element
germanium was only theorized to exist by Mendeleev in 1871. Fifteen years later, the element is
discovered in samples of a new mineral species, argyrodite! Argyrodite is not an ore of germanium due to
its rarity and the fact that sufficient germanium is recovered from the burning of coal and the refining of
zinc ores in which it is found as a trace element. Argyrodite gets its name from the Greek words that
loosely translate into "rich in silver".

Physical Properties of Argyrodite

Crystal System: Orthorhombic
Cleavage: None
Color: Black, Steel gray.
Density: 6.1 - 6.3, Average = 6.19
Fracture: Irregular/Uneven, Conchoidal
 Hardness: 2.5 - Finger Nail
Luster: Metallic
Streak: Grayish black
Specific Gravity is 6.2 - 6.5
Other Characteristics: Opaque

Chemical Properties
Formula: Ag GeS - Up to about 40 mol-% of the sulfur may be replaced by selenium.
8

Occurrence
In low-temperature polymetallic deposits with silver sulfosalts (Freiberg, Germany); in high-
temperature Sn-Ag deposits (Bolivia).

6. BOURNONITE
Bournonite consists of lead, copper, antimony, and sulfur; antimony may be replaced by arsen.
Due to on the cleavage of {110}, bournonite has regular twin crystal aggregates and the name is given
according to the similar shape with a wheel. It has high specific weight and grayish to black color and
cleavage with the crystal structure of wheel shape. Bournonite occurs in mild hydrothermal ve ins, used
for refining metals of copper, antimony, and lead.

Physical Properties
Crystal System: Orthorhombic
Crystal Form: Colomun or plates
Hardness: 2.5-3
Cleavage: {010} poor, shell shape to uneven
Fracture: Subconchoidal
Luster: Metallic
Color: Steel gray to black
Steak: Steel gray to black
Magnetism: Nonmagnetic
Specific Gravity: 5.7-5.9
Density: 5.7 - 5.9, Average = 5.8
Other Characteristics:
(1) Usually in wheel shaped crystal form (twin crystals), with grooved surface
(2) Opaque
(3) Easy to melt

Chemical Properties
Formula: PbCuSbS3
Class: Sulfosalt
Characteristics: Soluble to nitric acid, shown as green solution

Diagnostic Features
(1) Great specific gravity
 (2) Color and streak are steel gray.
(3) Wheel shaped crystal (twin)

Occurences
It occurs in hydrothermal veins, associated with galena, chalcopyrite, sphalerite, stibnite and
quartz.

Major Uses
Used for refining copper, antimony, and lead.

7. POLYBASITE
One of the four "ruby silvers".

Physical Properties of Polybasite

Crystal System: Monoclinic
Cleavage: {001} Poor
Color: Black, Dark ruby red.
Density: 4.6 - 5, Average = 4.8
Fracture: Uneven, Conchoidal
Hardness: 2.5-3 - Finger Nail-Calcite
Luster: Sub Metallic
Magnetism: Nonmagnetic
Streak: reddish black
Density: 6.1 g/cm3 (Measured)
6.36 g/cm3 (Calculated)
Other Characteristics: Opaque

Chemical Properties
Formula: [(Ag,Cu) (Sb,As) S ][Ag CuS ]
6 2 7 9 4

Diagnostic Properties
(1) much softer
(2) harder to polish

Occurrence
In silver viens of low to moderate temperature of formation.

Major Uses
An ore of silver and as mineral specimens.

8. PROUSTITE
Proustite is very similar to Pyrargyrite, and forms a series with it. Proustite is the arsenic -rich
member, and Pyrargyrite is the antimony-rich member. It is often not possible to visually distinguish
these two minerals from each other, though Proustite is usually lighter in color. It is named in honor of
Joseph Louis Proust (1754-1826), a French chemist famous for defining the law of definite proportions,
also known as Proust's Law.

Physical Properties of Proustite

Crystal System: Trigonal
Cleavage: None
Color: Vermilion, Reddish gray.
Density: 5.5 - 5.6, Average = 5.55
Fracture: Irregular/Uneven, Conchoidal
Hardness: 2-2.5 - Gypsum-Finger Nail
Luster: Sub Metallic
Magnetism: Nonmagnetic
Streak: vermilion red
Density: 5.57 g/cm3 (Measured)
5.625 g/cm3 (Calculated)

Chemical Properties
Formula: Ag3 AsS3

Diagnostic Features
(1) Brilliant, brick-red streak

Occurrence
Late forming mineral in hydrothermal deposits, in the oxidized and enriched zone, associated
with other silver minerals and sulfides.

Major Uses
A minor ore of silver, as mineral specimens and as a rare gemstone.

9. PYRARGYRITE
Pyrargyrite is a popular silver bearing mineral for collectors. Its color is a dark red and is most commonly
so dark that it appears black.

Physical Properties
Crystal System: Trigonal
Cleavage: {1011} Poor
Color: Deep red, Red gray.
Density: 5.85
Fracture: Irregular/Uneven, Conchoidal
Hardness: 2.5 - Finger Nail
Luster: Sub Metallic
Streak: cherry red
Density: 5.82 g/cm3 (Measured)
5.855 g/cm3 (Calculated)
 Other Characteristics: Opaque to translucent

Chemical Properties
Formula: Ag3 SbS3

Occurrence
Primary late-stage, low temperature minearal and formed by secondary enrichment.

Major Uses
It is an ore of silver and as mineral specimens.

10. STEPHANITE
Stephanite is an uncommon mineral that is composed with a significant portion of silver in its
structure. It is an important ore mineral and mined for its silver content, and is almost always found in in
known silver deposits. Stephanite mostly forms in massive ore habit that is uninteresting to collectors, but
it is important as an economic commodity for its silver content. However, it does occasionally form in
highly aesthetic and lustrous crystals that are highly valued among collections. Stephanite is named after
Archduke Stephen Francis Victor of Austria (1817-1867).

Physical Properties
Crystal System: Orthorhombic
Cleavage: {010} Imperfect, {021} Poor
Color: Lead gray, Black.
Density: 6.2 - 6.3, Average = 6.25
Fracture: Subconchoidal
Hardness: 2-2.5 - Gypsum-Finger Nail
Luster: Metallic
Magnetism: Nonmagnetic
Streak: black
Other Characteristics: Opaque

Chemical Properties
Formula: Ag5 SbS4

Occurrence
A late-stage mineral in hydrothermal silver deposits.

Major Uses
An ore of silver and as mineral specimens.