Descriptive Mineralogy Non-Silicates:

Carbonates

Classification of the Minerals• Non-Silicates

– Native Elements

–Halides– Sulfides– Carbonates– Sulfates– Phosphates– Oxides– Hydroxides

• Silicates– Orthosilicates– Sorosilicates– Cyclosilicates– Chain Silicates– Layer Silicates– Tektosilicates

Carbonates • Calcite Group• Aragonite Group• Dolomite Group• Other carbonates

Carbonate Periodic Table

Calcite Group

• Calcite CaCO3

• Magnesite MgCO3

• Siderite FeCO3 • Rhodochrosite MnCO3

• Smithsonite ZnCO3

Calcite Structure

• Space Group R-3c

• Divalent cation radius < 1.00Å

Calcite CaCO3

Calcite CaCO3

Occurrence: Sedimentary: Detrital and Evaporite limestones

Metamorphic: Marble

Low temperature hydrothermal.

Igneous: Carbonatites, Kimberlites

Uses: Building stone, Sculpture, Gravel and paving

Acid mine drainage mitigation

Rhodochrosite MnCO3

Occurrence: Low T Hydrothermal

Uses: Mineral Specimens

Siderite FeCO3Occurrence:Low temperature

hydrothermal.

Use; Minor ore of Fe

Magnesite MgCO3

Occurrence: olivine weathering

Uses: Chalk CO2 Sequestration?

Smithsonite ZnCO3

Occurrence: Oxidized Hydrothermal (after sphalerite)

Uses: Minor ore of Zn

Aragonite Group

• Aragonite CaCO3

• Strontianite CaCO3 • Witherite BaCO3

• Cerussite PbCO3

Aragonite Structure

• Space Group Pbnm

• Cation Radius > 1.00Å

Aragonite CaCO3

Occurrence: High pressure rocks

Some shells

Boiler scale

Uses: None

Strontianite SrCO3

Occurrence: Low T Hydrothermal

Uses: Principal source of Sr (used in fireworks, ammunition, flares)

Witherite BaCO3

Occurrence: Low T Hydrothermal

Uses: Rat Poison

Witherite transforms at RT from orthorhombic to trigonal

• Witherite (BaCO3)

• 0 GPa 8.0 GPa

Cerussite PbCO3

Occurrence: Oxidized Hydrothermal

Uses: Minor ore of Pb

Dolomite Group

• Dolomite CaMg(CO3)2

• Ankerite CaFe(CO3)2

Dolomite CaMg(CO3)2

Occurrence: Sedimentary, Igneous (carbonantites)

Uses: None

Other Carbonates• Malachite Cu2(CO3)(OH)2

• Azurite Cu3(CO3)2(OH)2

• Bastnasite CeCO3F

• Bastnasite REECO3F

Malachite Cu2CO3(OH)2

Occurrence: Low T Hydrothermal Supergene Cu

Uses: Minor ore of Cu, gems and ornaments

Azurite Cu3(CO3)2(OH)2

Occurrence: Low T Hydrothermal Supergene Cu

Uses: Minor ore of Cu, gems and ornaments

Bastnasite CeCO3F

Occurrence: Pegmatite

Uses: Principal Source of Rare Earth Elements

Bastnasite CeCO3F

Carbonate Periodic Table

Gossans are Oxidized Hydrothermal Deposits