amorphous Carbonates
Malachite (Massive (typical))
Formula Cu2(CO3)(OH)2
Crystal Structure
#! Species: Malachite
#! System: Amorphous (cryptocrystalline)
#! Habit: Botryoidal and mammillary with concentric banding
amorphous[cryptocrystalline]:{botryoidal, mammillary}[banding:concentric]
amorphous
2/m
{botryoidal, mammillary}
Quick Facts
Hardness
3.5
Specific Gravity
3.6
Refractive Index
1.655
Optical Character
Biaxial -
Physical Properties
- Crystal System
- amorphous
- Hardness (Mohs)
- 3.5
- Specific Gravity
- 3.6
- Cleavage
- Perfect {201}, fair {010}
- Fracture
- Subconchoidal to uneven
- Lustre
- Vitreous (crystals), silky to dull (massive)
Optical Properties
- Refractive Index
- 1.655
- Birefringence
- 0.245
- Optical Character
- Biaxial -
- Pleochroism
- Weak (light green to dark green)
Characteristics
Colours
Bright greenDark greenBanded green (alternating light/dark)
Localities
Democratic Republic of Congo (major source)ZambiaAustraliaArizona (USA - Bisbee)Russia (Urals - historic)Namibia
Crystal Forms
botryoidalmammillarybanded masses
Notes
Reacts with dilute HCl (effervescence); often found with azurite
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)