Dr.

Boddepalli Govindarao
 Classification of Ore Deposits

The ore minerals can be classified in

various formats based on the type and
chemistry of minerals, depth of
occurrence, morphology, relation to host
rocks, nature of mineralization,
structural control and genetic model

To gain a better understanding of

various types of mineral deposits and
to help formulate an appropriate and
successful exploration program
Classifications Based on the Type of Mineral

Sulfides and sulfosalts

Covellite – CuS
Chalcocite - Cu2S
Chalcopyrite - CuFeS2
Bornite – Cu5 FeS4
Tetrahedrite – (Cu,
Ag)12Sb4 S13
Galena - PbS
Sphalerite – (Zn,Fe)S
Cinnabar - HgS
Cobaltite - (Co, Fe)AsS
Molybdenite: -MoS2
Pentlandite: (Fe, Ni)9S8
Millerite – NiS
Realgar – AsS
Stibnite – Sb2S3
Sperrylite – PtAs2
Laurite – RuS2
Sulfides and sulfosalts Classifications Based on the Type of Mineral
Covellite – CuS
Chalcocite - Cu2S
Chalcopyrite - CuFeS2 Oxides and hydroxides
Bornite – Cu5 FeS4 Bauxite
Tetrahedrite – (Cu, Gibbsite - Al(OH)3
Ag)12Sb4 S13 Boehmite - (g-AlO(OH))
Galena - PbS Diaspore - (a-AlO(OH))
Sphalerite – (Zn,Fe)S Cassiterite - SnO2
Cinnabar - HgS Cuprite – Cu2O
Cobaltite - CoAsS Chromite - FeCr2O4
Molybdenite: -MoS2 Hematite - Fe2O3
Pentlandite: (Fe, Ni)9S8 Ilmenite - FeTiO3
Millerite – NiS Magnetite - Fe3O4
Realgar – AsS Pyrolusite -MnO2
Stibnite – Sb2S3 Rutile – TiO2
Sperrylite – PtAs2 Uraninite (pitchblende) - UO2
Laurite – RuS2
Sulfides and sulfosalts Classifications Based on the Type of Mineral
Covellite – CuS
Chalcocite - Cu2S Oxysalts
Oxides and hydroxides
Chalcopyrite - CuFeS2 Calcite – CaCO3
Bauxite
Bornite – Cu5 FeS4 Rhodochrosite – MnCO3
Gibbsite - Al(OH)3
Tetrahedrite – (Cu, Smithsonite – ZnCO3
Boehmite - (g-AlO(OH))
Ag)12Sb4 S13 Malachite – Cu2(OH)2CO3
Diaspore - (a-AlO(OH))
Galena - PbS Gypsum – CaSO4 .2H2O
Cassiterite - SnO2
Sphalerite – (Zn,Fe)S Scheelite - CaWO4
Cuprite – Cu2O
Cinnabar - HgS Wolframite - (Fe, Mn)WO4
Chromite - FeCr2O4
Cobaltite - (Co, Fe)AsS Apatite – Ca5(PO4)3 (F,Cl,OH)
Hematite - Fe2O3
Molybdenite: -MoS2 Ilmenite - FeTiO3
Pentlandite: (Fe, Ni)9S8 Magnetite - Fe3O4
Millerite – NiS Pyrolusite -MnO2
Realgar – AsS Rutile – TiO2
Stibnite – Sb2S3 Uraninite (pitchblende) - UO2
Sperrylite – PtAs2
Laurite – RuS2
Sulfides and sulfosalts Classifications Based on the Type of Mineral
Covellite – CuS
Chalcocite - Cu2S Oxysalts
Oxides and hydroxides
Chalcopyrite - CuFeS2 Calcite – CaCO3
Bauxite
Bornite – Cu5 FeS4 Rhodochrosite – MnCO3
Gibbsite - Al(OH)3
Tetrahedrite – (Cu, Smithsonite – ZnCO3
Boehmite - (g-AlO(OH))
Ag)12Sb4 S13 Malachite – Cu2(OH)2CO3
Diaspore - (a-AlO(OH))
Galena - PbS Gypsum – CaSO4 .2H2O
Cassiterite - SnO2
Sphalerite – (Zn,Fe)S Scheelite - CaWO4
Cuprite – Cu2O
Cinnabar - HgS Wolframite - (Fe, Mn)WO4
Chromite - FeCr2O4
Cobaltite - (Co, Fe)AsS Apatite – Ca5(PO4)3 (F,Cl,OH)
Hematite - Fe2O3
Molybdenite: -MoS2 Ilmenite - FeTiO3
Pentlandite: (Fe, Ni)9S8 Silicates
Magnetite - Fe3O4
Asbestos (Mg3(Si2O5)(OH)4)
Millerite – NiS Pyrolusite -MnO2 Beryl - Be3 Al2 (SiO3)6
Realgar – AsS Rutile – TiO2 Garnet – Fe3 Al2 (SiO4)3
Stibnite – Sb2S3 Uraninite (pitchblende) - UO2
Garnierite – mixture of the Ni-Mg-hydrosilicates
Sperrylite – PtAs2
Laurite – RuS2 Metals and native elements Kaolinite – Al4 Si4 O8 (OH)8
Gold – Au Sillimanite – Al2 SiO5
Halides Silver – Ag Spodumene – LiAlSi2 O6
Halite – NaCl Platinum-group metals – Pt, Pd, Ru
Talc – Mg3 Si4 O8 (OH)2
Sylvite – KCl Copper – Cu
Fluorite – CaF2 Carbon – C (diamond, graphite) Zircon – ZrSiO4
Classifications Based on the Use of the Metal or Ore Mineral
Class Element Mineral Composition
Ferrous metals Iron (Fe) Hematite Fe2O3
FeO.OH
Fe3O4
• Ferrous Metals Manganese (Mn) Pyrolusite MnO2
• Base Metals Chromium (Cr) Chromite FeCr2O4
Nickel (Ni) Pentlandite (Fe,Ni)9S8
• Precious Metals Garnierite (Ni,Mg)3Si2O5(OH)4
• High-technology Metals Molybdinum(Mo) Molybdenite MoS2
Vanadium (V) Magnetite (Fe,V)3O4
Aluminium Aluminium (Al) Gibbsite Al (OH)3
Base metals Copper (Cu) Chalcopyrite CuFeS2
Chalcocite Cuprite Cu2S
Tetrahedrite Cu2O
Metallic mineral deposits Malachite Azurite (Cu, Ag)10(FeZn)2Sb4S13
Native Copper CuCO3.Cu(OH)2
• e.g., deposits of copper, Cu3(CO3)2(OH)2
lead, zinc, iron, gold, etc. Cu
Zinc (Zn) Sphalerite (Zn, Fe)S
Lead (Pb) Galene PbS
Tin (Sn) Cassiterite SnO2
Precious metals Gold (Au) Native gold Au
Platinum (Pt) Alloys of platinum group
elments (PGE)
Nonmetallic (or industrial) Silver (Ag) Native Silver Ag
Argentite (Ag2S) Ag
mineral deposits Energy sources Uranium (U) Pitchblende UO2
• e.g., deposits of clay, mica, Coal (C) Coal C
High-technology metals Titanium (Ti) Imenite FeTiO3
fluorite, asbestos, garnet
Zirconium (Zr) Zircon ZiSiO4
etc.) Niobium (Nb), thorium Monazite, apatite and rare Nb, Th, La, Ce, Nd
(Th), rare earth elements minerals (bastna¨site,
pollusite, etc)
Lithium (Li) Spodumene LiAlSi2O6
 Lindgren’s classification of ore deposits

Depth Temperatu Occurrence Metals

re
Telethermal Near surface ±100 In sedimentary rocks or lava Pb, Zn, Cd, Ge
flows; open fractures, cavities,
joints. No replacement phenomena
Epithermal Near surface 50–200 In sedimentary or igneous rocks; Pb, Zn, Au, Ag,
to 1.5 km often in fault systems; simple veins or Hg, Sb, Cu,
pipes and stockworks; Se, Bi, U
little replacement phenomena
Mesothermal 1.2–4.5 km 200–400 Generally, in or near intrusive igneous Au, Ag, Cu, As,
rocks; associated with Pb, Zn, Ni,
regional faults; extensive replacement Co, W, Mo,
deposits or fracture fillings; tabular U etc
bodies, stockworks, pipes
Hypothermal 3–15 km 400–600 In or near deep-seated felsic plutonic Au, Sn, Mo, W,
rocks in deeply eroded areas. Fracture- Cu, Pb, Zn,
filling and replacement bodies; tabular or As
irregular shapes
 A Classification Based on the Ore-Forming Process

1. Magmatic: ores that form by the accumulation of minerals 2. Deposits associated with hydrothermal fluids: metals
that crystallize directly from magma. are mobilized within and precipitated from hot aqueous
(a) In mafic and ultramafic rocks fluids or various origins
• Chromite and platinum-group elements (PGE) in large layered (a) Cu-Mo-W deposits in granitic intrusions
intrusions (Bushveld in South Africa, Great Dyke in Zimbabwe) • Deposits of the type “porphyry” (porphyry copper)
• Chromite in ophiolites (b) Epigenetic deposits – minerals in veins or replacing host
• Cu-Ni-Fe sulfide in the layered intrusions (Sudbury, Noril’sk) rocks
• Sulfide Ni-Cu-Fe in komatiitic lavas • Cu, Zn, Pb, Mo, Ag, Au ores related to granitic rocks
• Diamonds in kimberlites • “orogenic” gold deposits
(b) Associated with felsic intrusions • Ag-Ni-Co-As-S deposits
• Cu ore in carbonatites (c) Volcanogenic massive sulfide (VMS) deposits
• REE, P, Nb, Li, Be etc in pegmatites and carbonatites (d) Deposits unrelated to magmatic activity
• Pb-Zn ore in limestone (Mississippi Valley Type)
• Sedimentary Exhalative (SEDEX) deposits
3. Sedimentary deposits: concentrations of detrital • Uranium deposits (Athabasca, Canada; Colorado, USA)
minerals or precipitates
(a) SEDEX – Pb-Zn sulfides
4. Deposits related to weathering
(b) Cu ores in sandstones
(a) Al laterites – bauxite
(c) BIF (banded iron formations)
(b) Ni laterite
(d) Evaporites, phosphatites, Li-rich brines, limestone
(c) “Supergene” ore enrichment
(e) Placer deposits
• Placer gold in rivers
• Ti, Zr in beach sands 5. Metamorphic deposits
• Diamonds in sand and gravel (a) Deposits in skarn
 Ore deposits at different tectonic settings

II. Deposits at convergent plate margins

I. Deposits at oceanic ridges (divergent plate margins) • Porphyry Cu-Mo deposits
• Volcanogenic massive sulfide deposits (Cu, Zn) • Base metal deposits (Cu, Pb, Zn, Mo).
• Exhalative deposits (Zn, Cu, Pb, Au and Ag). e.g. Red • Precious metals (Pt, Au, Ag).
Sea • Pb-Zn-Ag veins and contact metasomatic deposits
• Mn nodules (Mn, Ni, Cu, Co) • Other metals (Sn, W, Sb, Hg).
• Cr, PGE, asbestos in ultramafic rocks

IV. Deposits in intracontinental settings III. Deposits in cratonic rift systems

• Ni and PGE in layered intrusions • Deposits of Sn, fluorite, barite in granites
• Ti in anorthosites • Evaporites in rift basins
• Iron-oxide Cu-Au deposits • Carbonatites containing Nb, P, REE, U, Th and
• Pb-Zn-Ag deposits in limestones and clastic sediments other rare elements
• Sedimentary Cu deposits
• Ni, Al laterites
• Diamonds in kimberlites