Sinhalite | |
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General | |
Category | Mineral |
IMA symbol | Shl[1] |
Crystal system | Orthorhombic |
Identification | |
Color | White, gray, grayish-blue, pale to dark brown, yellow, yellowish-brown, greenish-brown, green, brownish-pink, pale pink |
Crystal habit | Grains, rolled pebbles, irregular masses. Rarely euhedral crystals. |
Cleavage | None |
Fracture | Conchoidal |
Mohs scale hardness | 6+1⁄2-7 |
Streak | White |
Diaphaneity | Transparent, translucent |
Specific gravity | 3.46 to 3.50 |
Density | 3.475-3.5 |
Optical properties | Biaxial (-) |
Refractive index | 1.665 to 1.712 |
Birefringence | 0.036 to 0.042 |
Pleochroism | Trichroism: green, light brown, dark brown |
2V angle | 56° |
Dispersion | 0.018 |
Ultraviolet fluorescence | None |
Sinhalite is a borate mineral with formula MgAl(BO4).[2]
Sinhalite was first found in Sri Lanka (Ceylon) in 1952, and was named from Sinhala - the Sanskrit name for Sri Lanka.[3]
Gemstone quality Sinhalite can also be found in Madagascar, Tanzania and Myanmar (Burma). The most commonly seen color of Sinhalite are white to gray, grayish-blue or a shade of brown ranging from pale to dark. Pale pink and brownish pink crystals can be found in Tanzania.