Difference between revisions of "Almandine"
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{{almandine}} | {{almandine}} | ||
| + | |||
| + | ==Diagnostics== | ||
| + | [[File:Almandine.jpg|thumb|left|300px|Oval, faceted Almandine garnet ]]<br clear="left" /> | ||
| + | |||
| + | ===Color=== | ||
| + | |||
| + | Brownish red, red to violet/purple | ||
| + | |||
| + | ===Spectroscope=== | ||
| + | |||
| + | Almandine has a typical iron spectrum | ||
| + | [[File:Almandine_spectrum.jpg|thumb|left|240px]]<br clear="left" /> | ||
| + | |||
| + | ===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=== | ||
| + | |||
| + | Almandine sinks in all common heavy liquids. | ||
| + | |||
| + | ===Optical effects=== | ||
| + | |||
| + | Almandine may show asterism and chatoyancy | ||
| + | |||
| + | ==Varieties== | ||
| + | |||
| + | ===Rhodolite=== | ||
| + | [[File:Rhodolite_Garnet_7.jpg|left|thumb|300px|Faceted Rhodolite Garnet <br /> Photo courtesy of Rick Martin]]<br clear="left" /> | ||
| + | Rhodolite is the purple (pinkish/violet) variety of pyrope-almandine. | ||
| + | <br clear="left" /> | ||
| + | |||
| + | ==Inclusions== | ||
| + | [[Image:Sk_garnet_silk.jpg|thumb|left|240px|Silk, crystals, and a crystal looking like a skull, inside of a pyrope-almandine garnet.<br />~85X Magnification<br /> ©Jamey Swisher]] | ||
| + | <br clear="left" /> | ||
| + | |||
| + | ==Localities== | ||
| + | |||
| + | India, USA, Brazil | ||
| + | |||
| + | ==Occurrence== | ||
| + | |||
| + | Metamorphic rocks | ||
Latest revision as of 18:33, 2 December 2012
| 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
Almandine 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.
Inclusions
Localities
India, USA, Brazil
Occurrence
Metamorphic rocks
