CaCO3 (aragonite) + conchiolinOrthorhombic (aragonite)
Pearl
CaCO3 (aragonite) + conchiolin
OrganicChemical FormulaCaCO3 (aragonite) + conchiolin
Crystal SystemOrthorhombic (aragonite)
Mohs Hardness2.5
Specific Gravity2.7
ColorWhite, cream, pink, black
LusterPearly
StreakWhite
CleavageNone
FractureUneven
Occurrence
Formed by mollusks. Organic gemstone. Cultured pearls from freshwater and saltwater oysters.