Introduction to Ore-Forming Processes. Laurence RobbЧитать онлайн книгу.

occurring in the native form include copper, silver, gold, and platinum which are all characterized by cubic close packing of atoms, high densities, and are malleable and soft. The carbon atoms in diamond are linked in tetrahedral groups forming well cleaved, very hard, translucent crystals. Sulfur also occurs as rings of eight atoms and forms bipyramids or is amorphous.

Metals

1 Gold – Au

2 Silver – Ag

3 Platinum – Pt

4 Palladium – Pd

5 Copper – Cu

Non‐metals

1 Sulfur – S

2 Diamond – C

3 Graphite – C

Halides

The halide mineral group comprises compounds made up by ionic bonding. Minerals such as halite and sylvite are cubic, have simple chemical formulae, and are highly soluble in water. Halides sometimes form as ore minerals, such as chlorargyrite and atacamite.

1 Halite – NaCl

2 Sylvite – KCl

3 Chlorargyrite – AgCl

4 Fluorite – CaF2

5 Atacamite – Cu2Cl(OH)3

Sulfides and Sulfosalts

This is a large group of minerals in which bonding is both ionic and covalent in character. The sulfide group has the general formula A_MX_P, where X is typically S but can be As, Sb, Te, Bi, or Se, and A is one or more of the metals. The sulfosalts, which are less common than sulfides, have the general formula A_MB_NX_P, where A is usually Ag, Cu, or Pb, B is commonly As, Sb, or Bi, and X is S. The sulfide and sulfosalt minerals are generally opaque, dense, and have a metallic to sub‐metallic luster.

Sulfides

1 Chalcocite – Cu2S

2 Bornite – Cu5FeS4

3 Galena – PbS

4 Sphalerite – ZnS

5 Chalcopyrite – CuFeS2

6 Pyrrhotite – Fe1–xS

7 Pentlandite – (Fe,Ni)9S8

8 Millerite – NiS

9 Covellite – CuS

10 Cinnabar – HgS

11 Skutterudite – (Co,Ni)As3

12 Sperrylite – PtAs2

13 Braggite/cooperite – (Pt,Pd,Ni)S

14 Moncheite – (Pt,Pd)(Te,Bi)2

15 Laurite – RuS2

16 Cobaltite – CoAsS

17 Gersdorffite – NiAsS

18 Loellingite – FeAs2

19 Arsenopyrite – FeAsS

20 Molybdenite – MoS2

21 Realgar – AsS

22 Orpiment – As2S3

23 Stibnite – Sb2S3

24 Bismuthinite – Bi2S3

25 Argentite – Ag2S

26 Calaverite – AuTe2

27 Pyrite – FeS2

Sulfosalts

1 Tetrahedrite – (Cu,Ag)12Sb4S13

2 Tennantite – (Cu,Ag)12As4S13

3 Enargite – Cu3AsS4

Oxides and Hydroxides

This group of minerals is variable in its properties but is characterized by one or more metals in combination with oxygen or a hydroxyl group. The oxides and hydroxides typically exhibit ionic bonding. The oxide minerals can be hard, dense, and refractory in nature (magnetite, cassiterite) but can also be softer and less dense, forming as products of hydrothermal alteration and weathering (hematite, anatase, pyrolusite). Hydroxides, such as goethite and gibbsite, are typically the products of extreme weathering and alteration.

Oxides

1 Cuprite – Cu2O

2 Hematite – Fe2O3

3 Ilmenite – FeTiO3

4 Hercynite – FeAl2O4

5 Gahnite – ZnAl2O4

6 Magnetite – Fe3O4

7 Chromite – FeCr2O4

8 Rutile – TiO2

9 Anatase – TiO2

10 Pyrolusite – MnO2

11 Cassiterite – SnO2

12 Uraninite – UO2

13 Thorianite – ThO2

14 Columbite‐tantalite – (Fe,Mn)(Nb,Ta)2O6

Hydroxides (or Oxyhydroxides)

1 Goethite – FeO(OH)

2 Gibbsite – Al(OH)3

3 Boehmite – AlO(OH)

4 Manganite – MnO(OH)

Oxysalts

The carbonate group of minerals form when anionic carbonate groups images are linked by intermediate cations such as Ca, Mg, and Fe. Hydroxyl bearing and hydrated carbonates can also form, usually as a result of weathering and alteration. The other oxysalts, such as the tungstates, sulfates, phosphates, and vanadates, are analogous to the carbonates, but are built around an anionic group in the form images .

Carbonates

1 Calcite – CaCO3

2 Dolomite – CaMg(CO3)2

3 Ankerite – CaFe(CO3)2

4 Siderite – FeCO3

5 Rhodochrosite – MnCO3

6 Smithsonite – ZnCO3

7 Cerussite – PbCO3

8 Azurite – Cu3(OH)2(CO3)2

9 Malachite – Cu2(OH)2CO3

Tungstates

1 Scheelite – CaWO4

2 Wolframite – (Fe,Mn)WO4

Sulfates

1 Baryte(s) – BaSO4

2 Anhydrite – CaSO4

3 Alunite – KAl3(OH)6(SO4)2

4 Gypsum – CaSO4·2H2O

5 Epsomite – MgSO4·7H2O

Phosphates

1 Xenotime – YPO4

2 Monazite – (Ce,La,Th)PO4

3 Apatite – Ca5(PO4)3(F,Cl,OH)