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Sinhalite

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Sinhalite
General
CategoryMineral
IMA symbolShl[1]
Crystal systemOrthorhombic
Identification
ColorWhite, gray, grayish-blue, pale to dark brown, yellow, yellowish-brown, greenish-brown, green, brownish-pink, pale pink
Crystal habitGrains, rolled pebbles, irregular masses. Rarely euhedral crystals.
CleavageNone
FractureConchoidal
Mohs scale hardness6+12-7
StreakWhite
DiaphaneityTransparent, translucent
Specific gravity3.46 to 3.50
Density3.475-3.5
Optical propertiesBiaxial (-)
Refractive index1.665 to 1.712
Birefringence0.036 to 0.042
PleochroismTrichroism: green, light brown, dark brown
2V angle56°
Dispersion0.018
Ultraviolet fluorescenceNone

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.

References

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  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ "Sinhalite". Mindat.org.
  3. ^ "Sinhalite gemstone information". Gemdat.org. Retrieved 21 March 2019.