MICROLITE: Brazil (0.14)
Microlite is usually opaque to translucent and is cut into cabochons by collectors. Faceted gems are very beautiful and extremely rare. Green Brazilian gems weighing less than 1 carat have appeared on the market and the potential exists there for larger stones.
Microlite Value
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Microlite Information
| Data | Value |
| Name | Microlite |
| Crystallography | Lsometric. Crystals octahedral; also grains and masses. |
| Colors | Pale yellow to brown, reddish, green. |
| Luster | Vitreous to resinous. |
| Hardness | 5-5.5. |
| Density | 4.3-5.7; usually 5.5. |
| Cleavage | Octahedral (not always evident). Fracture subconchoidal to uneven. Brittle. |
| Stone Sizes | Cabochons can be cut to several inches in length (brownish or reddish massive material). Faceted gems are generally under 3-4 carats in weight; larger would be extremely rare. A crystal found in 1885 was garnet red in color, weighed 4.4 carats in the rough, and was cut into a stone that looked like a red zircon. Smithsonian Institution (Washington, D.C): 3.7 (brown. Virginia). |
| Luminescence | None. |
| Spectral | Not diagnostic. |
| Formula | (Na,Ca)2Ta2O6(O,OH.F) |
Pyrochlore Group.
Streak: Pale yellow to brown.
Optics: N=1.93-1.94 if slightly metamict; also 1.98-2.02. Metamictization may cause anomalous birefringence.
Occurrence: Primary mineral in granite pegmatites.
Connecticut; Maine; Massachusetts; South Dakota; Colorado; New Hampshire.
Greenland; Norway; Sweden; Finland; France; Madagascar; Western Australia.
Amelia, Virginia (Rutherford Mines): green and brown crystals, some gemmy ones up to a few inches in length.
Brazil: fine green crystals, some gemmy.
Comments: Microlite is usually opaque to translucent and is cut into cabochons by collectors. Faceted gems are very beautiful and extremely rare. Green Brazilian gems weighing less than 1 carat have appeared on the market and the potential exists there for larger stones.
Name: From the Greek mikros (small), due to the small size of the crystals found at the original locality.
