Carbonates

Anion group for carbonate minerals

[CO₃]^-2

Structural properties for carbonate minerals

Triangle coordination, links with larger cations

General properties of carbonate minerals

Birefringence, high order interference color, most stable salts of carbonic acid

Carbonate mineral sub-groups

Calcite group, aragonite group, dolomite group

Structural properties of calcite

6 fold CN, 3 directional rhombohedral cleavage, several crystal habits

Chemical formula of calcite

CaCO₃

General properties of calcite

Vitreous luster, colors vary, hardness 3

Places of occurrence for calcite

Dominate mineral in carbonate rocks

Structural properties for siderite

Rhombohedral crystals, granular aggregates

Chemical formula for siderite

FeCO₃

General properties of siderite

Vitreous luster (very), rusty-yellow-brown color

Places of occurrence for siderite

Hydrothermal medium temperature veins, and chemically in sedimentary rocks

Structural/chemical properties for magnesite

End member in isomorphic series

Chemical formula for magnesite

MgCO₃

General properties for magnesite

Gray-ish white

Places of occurrence of magnesite

White-porcelain-like veins, product of serpentinite weathering

General properties for rhodochrosite

Pale pink-reddish color, indicator of the great oxygenation event.

Chemical formula for rhodochrosite

MnCO₃

Places of occurrence for rhodochrosite

Hydrothermal deposits and in sedimentary manganese deposits

Structural properties of aragonite

Orthorhombic system, prismatic or tabular crystals, cyclic twinning common, high-pressure polymorph of calcite

Chemical formula of aragonite

CaCO₃

General properties of aragonite

Vitreous luster, white, yellow-white, brown or gray, hardness 4

Places of occurrence for aragonite

Coral & mollusk shells, with calcite, in stalactites and stalagmites out of supersaturated solutions

Structural properties for dolomite

Orthorhombic, layers of Mg and Ca alternate along the c-axis

Chemical formula for dolomite

CaMg(CO₃)₂

Chemical properties of dolomite

Solid solution with calcite ONLY at high temperatures

General properties of dolomite

White, rusty brown, hardness 4, fizzes only when powered, usually a secondary mineral

Places of occurrence of dolomite

Low-med temperature hydrothermal deposits and in sedimentary deposits

Structural properties of azurite

Granular, crystalline, or globular aggregates

Chemical formula for azurite

Cu₃(CO₃)₂(OH₂)

General properties of azurite

Blue 🩵💙

Places of occurrence for azurite

Hydrothermal, associated with malachite

Structural properties of malachite

Kidney-shaped aggregates, pseudomorphs after native Cu, cuprite, and azurite

Chemical formula for malachite

Cu₂CO₃(OH₂)

General properties of malachite

Green, mineral of the oxidation zone of chalcopyrite and other copper sulfide deposits

Places of occurrence for malachite

Hydrothermal deposits, oxidation zone of chalcopyrite and other copper sulfide deposits