Difference between revisions of "Almandine"
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{{almandine}} | {{almandine}} | ||
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+ | ==Diagnostics== | ||
+ | |||
+ | ===Color=== | ||
+ | |||
+ | Brownish red, red to violet/purple | ||
+ | |||
+ | ===Spectroscope=== | ||
+ | |||
+ | Almandine has a typical iron spectrum | ||
+ | |||
+ | ===Inclusions=== | ||
+ | |||
+ | * Short rutile needles in 3 directions | ||
+ | * Crystals surrounded by stress cracks | ||
+ | * Irregular and rounded crystals | ||
+ | |||
+ | ===Polariscope=== | ||
+ | |||
+ | Almandine is isotropic but may have a small DR. | ||
+ | |||
+ | ===Specific gravity=== | ||
+ | |||
+ | Sinks in all common heavy liquids | ||
+ | |||
+ | ===Optical effects=== | ||
+ | |||
+ | Almandine may show asterism and chatoyancy | ||
+ | |||
+ | ==Varieties== | ||
+ | |||
+ | ===Rhodolite=== | ||
+ | |||
+ | Rhodolite is the purple (pinkish/violet) variety of pyrope-almandine. | ||
+ | |||
+ | ==Localities== | ||
+ | |||
+ | India, USA, Brazil | ||
+ | |||
+ | ==Occurance== | ||
+ | |||
+ | Metamorphic rocks |
Revision as of 10:16, 13 December 2006
Almandine Garnet | |
---|---|
Chemical composition | Fe3Al2(SiO4)3
Iron aluminum silicate |
Crystal system | Cubic |
Habit | Dodecahedra |
Cleavage | None |
Hardness | 7.5 |
Optic nature | Isotropic |
Refractive index | 1.78-1.81 |
Birefringence | None |
Specific gravity | 3.95 - 4.20 |
Lustre | Vitreous |
Contents
Diagnostics
Color
Brownish red, red to violet/purple
Spectroscope
Almandine has a typical iron spectrum
Inclusions
- Short rutile needles in 3 directions
- Crystals surrounded by stress cracks
- Irregular and rounded crystals
Polariscope
Almandine is isotropic but may have a small DR.
Specific gravity
Sinks in all common heavy liquids
Optical effects
Almandine may show asterism and chatoyancy
Varieties
Rhodolite
Rhodolite is the purple (pinkish/violet) variety of pyrope-almandine.
Localities
India, USA, Brazil
Occurance
Metamorphic rocks