Holtite Value, Price, and Jewelry Information


This mineral was first noted in 1937 but was not described in detail until 1971. It has not yet been seen as a gem, but the high hardness would allow it be worn with no risk of scratching. Holtite is now considered to be a variety of dumortierite. The mineral comes from the one locality, and a cut stone would have to be considered a great rarity.

Holtite Value

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Holtite Information

DataValue
NameHoltite
Crystallography Orthorhombic. Compact pebbles of acicular crystals, 2-15 mm diameter. Needles often in parallel arrangement.
Colors Cream white, buff, olive green, brownish.
Luster Dull to resinous
Hardness 8.5
Specific Gravity 3.90
Birefringence 0.015
Cleavage Good 1 direction.
Stone SizesCould yield cabochons up to about 1 inch.
Luminescence Dull orange in SW, bright yellow in LW.
FormulaAl6(Ta,Sb,Li)[(Si,As)O4]3(BO3)(O,OH)3 + Fe, Be, Ti, Mn, and Nb. Related to dumortierite.
Pleochroism Distinct: yellow/colorless/colorless.

Optics: a= 1.743-1.746;  β= 1.756-1.759; γ= 1.758-1.761.

Biaxial (-), 2V= 49-55°.

Occurrence: Alluvial tin deposit near Greenoushes, Western Australia, associated with cassiterite.

Comments: This mineral was first noted in 1937 but was not described in detail until 1971. It has not yet been seen as a gem, but the high hardness would allow it be worn with no risk of scratching. Holtite is now considered to be a variety of dumortierite. The mineral comes from the one locality, and a cut stone would have to be considered a great rarity.

Name: After Harold E. Holt, prime minister of Australia from 1966 to 1967.