Almandine (Rhombic Dodecahedron) crystal structure
cubic Nesosilicates

Almandine (Rhombic Dodecahedron)

Fe3Al2(SiO4)3

Quick Facts

Hardness
7.0
Specific Gravity
4.05
Refractive Index
1.78
Optical Character
Isotropic

Crystal Structure

#! Species: Almandine #! System: Cubic (m3m) #! Habit: Rhombic dodecahedron cubic[m3m]:{110}
cubic
m3m
{110}

Physical Properties

Crystal Systemcubic
Hardness (Mohs)7.0
Specific Gravity4.05
CleavageNone
FractureConchoidal to uneven
LustreVitreous to resinous

Optical Properties

Refractive Index1.78
Optical CharacterIsotropic
Dispersion0.024
PleochroismNone (isotropic)

Colours

Deep redBrownish-redPurplish-redDark red

Localities

IndiaSri LankaBrazilMadagascarUSA (Idaho)Mozambique

Common Inclusions

Rutile needles (silk)Rounded crystalsFingerprint inclusions

Known Treatments

None commonly applied

Crystal Forms

dodecahedron

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#! Species: Almandine #! System: Cubic (m3m) #! Habit: Rhombic dodecahedron cubic[m3m]:{110}