Biominerals

A crystal of calcite (a polymorph of calcium carbonate CaCO₃) one of a few attractive bio-minerals

Classified by oxoacid salt anion

Carbonates

calcium carbonate (sea shells, corals, ...):

• calcite CaCO₃ – [1] – Mohs 3 (defining mineral) – trigonal
• aragonite CaCO₃ – [2] – Mohs 3.5-4.0 – orthorhombic

Phosphates

calcium phosphate with crystal water (bones, enamel, ...)

• hydroxy-appatipe – [3] – Mohs 5 (defining mineral) – hexagonal

Wikipedia: (apatite)

Silicates

• hydroxy-silicates – diatoms (tiny glass making sea creatures)

(Quartz is the defining mineral for Mohs 7. Biogenic silica is likely softer though. To check.)

Sulfates (quite soft and soluble)

• gypsum CaSO₄·2H₂O – [4] – Mohs 2 (defining mineral) – monoclinic
• baryte BaSO₄ – [5] – Mohs 3.0-3.5 – 4.3g/ccm-5.0g/ccm – orthorhombic
• celestine SrSO₄ – [6] – Mohs 3-.0-3.5 – 3.95g/ccm-3.97g/ccm – orthorhombic

Simple Salts

• Fluorite CaF₂ – Mohs 4 (defining mineral) – cubic

Iron minerals

• pyrite FeS₂ – [7] – Mohs 6.0-6.5 – cubic
• marcasite FeS₂ – [8] – Mohs 6.0-6.5 – orthorhombic
• magnetite Fe₃O₄ – [9] – Mohs 5.5-6.5 – cubic
• greigite Fe₃S₄ – [10] – Mohs 4.0-4.5 – cubic
• goethit FeO(OH) [11] – [12] – Mohs 5.9-5.5 – orthorhombic

Related

• gemstone-like compounds
• Iron cluster
• Zinc finger

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• Wikipedia: Mohs_scale_of_mineral_hardness

Remaining Mohs scale defining minerals (not as bio-minerals)

• 6 orthoclase
• 7 (abiotic) quartz
• 8 topaz
• 9 sapphire (= corundum)
• 10 diamond

Related

• In solvent synthesizable gemstone-like compounds
• Technology level II
• Biomineralization
• Polyoxymetalates

External links

Wikipedia:

• Biomineralization
• Diatoms
• Biogenic_silica
• Bone_mineral

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Interesting reprocessing use of bio-minerals:

• Bone_china