Simpsonite Value, Price, and Jewelry Information

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SIMPSONITE: Brazil (0.27). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Simpsonite

Simpsonite is an extremely rare gemstone. The material from Western Australia is bright yellow-orange and very beautiful. The mineral is hard and durable, with no cleavage, and could easily become a popular gemstone if it were more abundant. Gems over 1 carat should be considered extremely rare because clean material is a very small percentage of the limited supply of simpsonite that has been found.

Simpsonite Information

Data	Value
Name	Simpsonite
Stone Sizes	Crystals have been found up to 5 cm but only tiny stones have been cut from available rough. Ln general, stones are only seen from Brazil and Australia. A typical size is 0.5-1 carat.
Formula	Al₄Ta₃O₁₃(OH).
Colors	Colorless, pale yellow, cream white, light brown, orange.
Fracture	Conchoidal
Hardness	7-7.5
Cleavage	None
Crystallography	Hexagonal. Crystals tabular, prismatic; also in crystalline masses.
Refractive Index	1.976-2.034
Birefringence	0.058
Luminescence	In SW, bright blue-white (Western Australia), bright pale yellow (Bikita, Zimbabwe), medium pale yellow (Ecuador) or light blue (Paraiba, Brazil).
Luminescence Present	Yes
Luminescence Type	Fluorescent, UV-Short
Absorption Spectrum	Not diagnostic.
Pleochroism	None.
Optics	o = 2.034; e = 1.976. Uniaxial (-).
Optic Sign	Uniaxial -
Luster	Vitreous, adamantine.
Specific Gravity	5.92-6.84
Transparency	Transparen to translucent.

Optics: o= 2.034; e=1.976.

Uniaxial (-).

Occurrence: In granite pegmatites, usually with biotite.

Bikita, Zimbabwe; Alto do Giz, Ecuador; Kola Peninsula, USSR.

Onca and Paraiba, Brazil: facetable material.

Tabba Tabba. Western Australia: facetable yellowish crystals.

Comments: Simpsonite is an extremely rare gemstone. The material from Western Australia is bright yellow-orange and very beautiful. The mineral is hard and durable, with no cleavage, and could easily become a popular gemstone if it were more abundant. Gems over 1 carat should be considered extremely rare because clean material is a very small percentage of the limited supply of simpsonite that has been found.

Name: After Dr. E. S. Simpson, former government mineralogist of Western Australia.