amorphous Carbonates
Rhodochrosite (Banded Massive)
Formula MnCO3
Crystal Structure
#! Species: Rhodochrosite
#! System: Amorphous (cryptocrystalline)
#! Habit: Mammillary with concentric pink banding
amorphous[cryptocrystalline]:{mammillary}[banding:concentric, colour:pink]
amorphous
-3m
{mammillary}
Quick Facts
Hardness
3.5
Specific Gravity
3.45
Refractive Index
1.597
Optical Character
Uniaxial -
Physical Properties
- Crystal System
- amorphous
- Hardness (Mohs)
- 3.5
- Specific Gravity
- 3.45
- Cleavage
- Perfect {1011} (rhombohedral)
- Fracture
- Uneven to conchoidal
- Lustre
- Vitreous to pearly
Optical Properties
- Refractive Index
- 1.597
- Birefringence
- 0.218-0.220
- Optical Character
- Uniaxial -
- Dispersion
- 0.015
- Pleochroism
- moderate: Pinkish-red / Orangy-pink (Best seen in transparent faceted material)
Characteristics
Colours
Rose pinkDeep pinkRedRaspberry redBanded pink/whiteOrange-pink
Localities
Colorado (USA - Sweet Home Mine)Argentina (Capillitas - banded)South Africa (N'Chwaning)PeruRomaniaJapan
Crystal Forms
mammillarybanded masses
Notes
Argentine banded material ("Rosa del Inca") formed in historic Inca silver mines
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)