amorphous Mineraloid
Pearl (nacre)
CaCO3 (aragonite) + conchiolin
Quick Facts
Hardness
2.5
Specific Gravity
2.6
Refractive Index
1.52
Optical Character
Biaxial -
Crystal Structure
#! Species: Pearl
#! System: Amorphous (organic aggregate)
#! Habit: Mammillary with concentric nacre banding
amorphous[waxy]:{mammillary}[banding:concentric]
amorphous
mmm
{mammillary}
Physical Properties
Crystal Systemamorphous
Hardness (Mohs)2.5
Specific Gravity2.6
FractureUneven
LustrePearly (nacreous)
Optical Properties
Refractive Index1.52
Optical CharacterBiaxial -
PleochroismNone
Colours
WhiteCreamPinkGold (South Sea)Black (Tahitian)SilverBlue-greyOvertones (rose, green, orient)
Localities
Persian Gulf (natural, historic)Japan (Akoya cultured)Australia (South Sea)Tahiti (black pearls)China (freshwater)Philippines
Known Treatments
BleachingDyeingIrradiation (for color)Coating
Crystal Forms
mammillaryconcentric layers
Notes
Organic gem — layered nacre aggregate, not a single crystal
Interactive Preview
Open this crystal in the CDL Playground to rotate, export, and explore in 3D.
Open in Playground #! Species: Pearl
#! System: Amorphous (organic aggregate)
#! Habit: Mammillary with concentric nacre banding
amorphous[waxy]:{mammillary}[banding:concentric]
Related Minerals
Other minerals in the amorphous system
