cubic Nesosilicates
Demantoid
Ca3Fe2(SiO4)3:Cr
Quick Facts
Hardness
6.5
Specific Gravity
3.82
Refractive Index
1.888
Optical Character
Isotropic
Crystal Structure
#! Species: Demantoid (Andradite Garnet)
#! System: Cubic (m3m)
#! Habit: Trapezohedron with diagnostic horsetail inclusions
cubic[m3m]:{211}@1.0[inclusion:horsetail] + {110}@0.7
cubic
m3m
{211} {110}
Physical Properties
Crystal Systemcubic
Hardness (Mohs)6.5
Specific Gravity3.82
CleavageNone
FractureConchoidal to uneven
LustreAdamantine to vitreous
Optical Properties
Refractive Index1.888
Optical CharacterIsotropic
Dispersion0.057
PleochroismNone (isotropic)
Colours
Vivid greenYellowish-greenGrass greenDeep green
Localities
Russia (Ural Mountains)NamibiaMadagascarIranItaly
Common Inclusions
Horsetail (byssolite/chrysotile fibres)Diopside crystalsMagnetite octahedra
Known Treatments
Heat treatment (rare, can improve colour)Generally not treated
Crystal Forms
trapezohedrondodecahedron
Interactive Preview
Open this crystal in the CDL Playground to rotate, export, and explore in 3D.
Open in Playground #! Species: Demantoid (Andradite Garnet)
#! System: Cubic (m3m)
#! Habit: Trapezohedron with diagnostic horsetail inclusions
cubic[m3m]:{211}@1.0[inclusion:horsetail] + {110}@0.7
Related Minerals
Other minerals in the cubic system
