Earth Materials: Minerals

Presentation on theme: "Earth Materials: Minerals"— Presentation transcript:

1 Earth Materials: Minerals

2 There are roughly 3000 minerals in the crust (lithosphere) but only a handful are commonly found!
Minerals can be made of one element, monomineralic (ex: Iron- Fe) or a polymineralic meaning a compound ( ex: SiO2 -quartz) A Mineral: is a naturally occurring, inorganic (not made by living things), homogenous (uniform) substance with a definite crystal structure.

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4 How are Minerals formed?
1.) Cooling and solidification of molten rock: atoms arrange themselves as magma/lava cools Examples: quartz, muscovite, feldspars 2.) Re-crystalization: Atoms rearrange themselves in already existing minerals when there is an increase in temperature and/or pressure. examples: graphite turns to diamond! 3.) Precipitation : mineral comes out of solution in supersaturated water with dissolved elements evaporation of saltwater from oceans/lake beds form halite (called“evaporites”) Calcite deposits form from supersaturated water in oceans and in caves

5 Minerals are identified by:
1.) Chemical Properties/Composition: What the mineral is made of (example: Graphite is made of ________) 2.) Physical Properties : Color, hardness, shape, streak, breakage, etc. *A minerals physical properties are always determined by the internal arrangement of the atoms (how they are organized)

6 Minerals can have the same chemical ingredients, yet be different in physical properties! Ex: Diamond vs. Graphite

7 Physical Characteristics For Mineral Identification

8 Color The appearance of the mineral
However there are issues with using a color for identification: FLAW #1 – different minerals can have the same color FLAW #2 – the same mineral can be different colors! Variations in color caused by impurities that get into the mineral as it’s forming! Color Fe Air, Water, CO2 Pure SiO2

9 (2)Non-metallic Waxy Pearly, translucent Earthy /Dull Glassy/Vitreous Luster- the way light is reflected from the surface (NOT HOW SHINY IT IS!) (1)Metallic= looks like metal

10 Crystal Habit/Shape Shape/Habit is not always shown by every mineral because minerals can grow in imperfect conditions. This means tight spaces underground and perhaps not enough time to grow! Halite (NaCl)=cubic Calcite (CaCO2)= rhombohedron

11 Fluorite=octahedron crystal habit
Quartz: Prismatic crystal habit Garnet: Octahedral

12 Streak Pyrite Vs. Gold: Was one of the ways for testing if it was true gold during the gold rush The color of a mineral’s powder left behind after scratching a “streak plate” (unglazed porcelain tile)

13 Mineral Breakage: always look on the edges of minerals to distinguish this property!
Fracture If it breaks with uneven or jagged surfaces (bumpy) Cleavage If a mineral breaks along smooth, even surfaces

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16 Hardness (most reliant)
A mineral’s resistance to being scratched On a scale from 1-10 A mineral is said to be hard if it scratches glass (hardness equal or greater than 5) A mineral is said to be soft if it can not scratch glass (hardness less than 5)

17 Other Mineral Properties & Identifying Characteristics

18 acid test Certain minerals react (bubble) with hydrochloric acid (HCl)
A great way for identifying CALCITE!

19 Special properties of some minerals
Certain minerals are easily identified by special properties Fluorite: glows under a black light Sulfur: bright yellow color, rotten egg smell Calcite: double refraction, reacts with HCl Halite: tastes like salt Magnetite: is magnetic

20 Mineral Groups 1.) Silicates
Minerals containing OXYGEN & SILICON – the 2 most abundant elements in the crust These atoms combine to form the silica-oxygen tetrahedron (SiO4) Look in your ESRT pg. 16 to list all silicate minerals found!

21 2.)Iron Oxides Certain minerals contain large amount of IRON (Fe)
When these minerals combine with Oxygen, the result is IRON OXIDE (rust) Ex: Hematite, Magnetite

22 3.) Carbonates Minerals containing a metallic element and a Carbonate compound CO3 Ex: Calcite, CaCO3 Found in Limestone and Marble These minerals break down with acid rain and acidic ground water

23 Q: Overall, what DETERMINES a mineral’s physical properties?
Your ESRT pg 16 lists all the mineral information you will need to identify an unknown mineral sample! Q: Overall, what DETERMINES a mineral’s physical properties?

24 Common Uses of Minerals
Garnet - jewelry (NYS gem), abrasives Halite - food additive, melts ice Quartz - glass, jewelry, electronics, abrasives Calcite - cement, toothpaste Gypsum- Drywall, cement, plaster of paris Talc- baby powder, lubricanthttps:// Garnet, North Creek, NY