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Hyalophane or jaloallofane is a crystalline mineral with chemical formula (K,Ba)[Al(Si,Al)Si2O8] and a hardness of 6 – 6½. It is part of the feldspar group of tectosilicates, and is considered a Barium-rich Potassium feldspar. Hyalophane comes from the Greek hyalos, meaning "glass", and phanos meaning "to appear".
Additional recommended knowledge
An occurrence of hyalophane was discovered in 1855 in Lengenbach Quarry, Imfield, in the municipality of Binn, Switzerland. The mineral is found predominantly in Europe, with occurrences in Switzerland, Australia, Bosnia, Germany, Japan, New Jersey, and the west coast of North America.
Hyalophane has a monolinic crystallography, with cell properties a = 8.52Å, b = 12.95Å, c = 7.14Å and β = 116°. Optically, the material exhibits biaxial birefringence, with refractive index values of nα = 1.542, nβ = 1.545, and nγ = 1.547 and a maximum birefringence of δ = 0.005. It has weak dispersion and low surface relief.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Hyalophane". A list of authors is available in Wikipedia.|