Flattened and Rotated Crystals in Muscovite Schist
Connecticut
Garnet
Garnet
Garnet
Muscovite Schist
Identification Tips
1. Almandine, like the other types of garnet, appear as dodecahedral (12-sided) or icositetrahedral (24-sided) crystals, usually in association with or embedded in metamorphic rocks (see picture). Therefore, most garnet crystals reveal some measure of deformation, usually flattening or fracturing.
2. Almandine is as hard as quartz and will scratch a streak plate.
3. Almandine possesses a very deep ruby-red color and a vitreous (glassy) luster.
4. Almandine does not possess a genuine crystal cleavage but may reveal a series of closely spaced parallel fractures produced in the crystal in response to metamorphic stresses.
5. Almandine reveals a rounded fracture surface on broken crystals, similar to that produced on a surface of broken glass.
Diagnostic Features
Hardness: 7
Streak: None
Luster: Nonmetallic
Specific Gravity: 4.3
Cleavage: None
Fracture: Conchoidal (rounded)
Other: Frequently as deep red,
vitreous, 12- and 24-sided crystals. Usually appear as flattened and rotated grains in metamorphic rocks.
