Organic

3 minerals in this group.

Pearl

CaCO3 (aragonite) + conchiolin

H: 2.5SG: 2.7Orthorhombic (aragonite)

Coral

CaCO3 (calcite/aragonite)

H: 3.5SG: 2.7Trigonal/Orthorhombic

Ivory

Ca5(PO4)3(OH) + collagen

H: 2.5SG: 1.8Hexagonal