amorphous Inosilicates
Nephrite (Massive (gem-quality))
Formula Ca2(Mg,Fe)5Si8O22(OH)2
Crystal Structure
#! Species: Nephrite
#! System: Monoclinic (2/m)
#! Habit: Massive interlocking fibrous aggregate
amorphous[cryptocrystalline]:{massive}
amorphous
2/m
{massive}
Quick Facts
Hardness
6.0
Specific Gravity
2.9
Refractive Index
1.6
Optical Character
Aggregate
Physical Properties
- Crystal System
- amorphous
- Hardness (Mohs)
- 6.0
- Specific Gravity
- 2.9
- Cleavage
- Good {110} at 56° (in individual fibres)
- Fracture
- Splintery (extremely tough)
- Lustre
- Greasy to waxy
Optical Properties
- Refractive Index
- 1.6
- Birefringence
- 0.027
- Optical Character
- Aggregate
Characteristics
Colours
Green (varies from pale to dark)White (mutton fat)GreyBrownBlackYellow
Localities
New ZealandChina (Khotan)Canada (British Columbia)Russia (Siberia)AustraliaTaiwan
Common Inclusions
Fibrous interlocking texture (tremolite-actinolite)Black magnetite/chromite specksTremolite fibres
Known Treatments
Wax treatmentDyeingPolymer impregnation
Crystal Forms
massive
Diagnostic Features
Lower RI and SG than jadeite; extremely tough; fibrous tremolite-actinolite; no 437nm absorption
Related Minerals
Other minerals in the amorphous system
Ambroid (Pressed Amber)
Compressed and fused amber chips (same chemical composition as amber — fossil resin; succinite for Baltic amber)
Bone (Ivory Simulant)
Ca5(PO4)3(OH) (hydroxyapatite; same general composition as ivory dentine) in collagen matrix; technically microcrystalline hydroxyapatite but gemologically treated as amorphous/aggregate biomineral
Chalcedony (Botryoidal)
SiO2
Chalcedony (Massive)
SiO2
Chrysocolla
(Cu,Al)2H2Si2O5(OH)4.nH2O
Copal (Amber Simulant)
Partially polymerised plant resin (labdanoid diterpenes; younger resin; not fully matured/polymerised)