Fluor-uvite

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Fluor-uvite
Uvite-165787.jpg
General
Category Cyclosilicate
tourmaline group
Formula
(repeating unit)
CaMg3(Al5Mg)(Si6O18)(BO3)3(OH)3F
Strunz classification 09.CK.05
Identification
Color Black, greenish-black, brownish-black, brown, green, colourless
Crystal system Trigonal
Cleavage None Observed
Fracture Irregular/Uneven, Conchoidal
Tenacity Brittle
Mohs scale hardness 7.5
Luster Vitreous, Resinous
Streak Light-brown, light-green, or white
Diaphaneity Transparent, Translucent
Density 2.97 - 3.14 g/cm3
Optical properties Uniaxial (-)
Birefringence δ = 0.018 - 0.029
Pleochroism Weak
References [1]

Fluor-uvite[2] is a tourmaline mineral with the chemical formula CaMg3(Al5Mg)(Si6O18)(BO3)3(OH)3F. It is a rare mineral that is found in calcium rich contact metamorphic rocks with increased amounts of boron.[3] Uvite is trigonal hexagonal, which means that it has three equal length axes at 120 degrees, all perpendicular to its fourth axis which has a different length. Uvite is part of the space group 3m.[4] Uvite's hardness has been measured to be 7.5 on the Mohs hardness scale. The color of uvite widely varies, depending on the sample, but is mostly deep green or brown. In regards to uvite's optical properties, it is uniaxial (-) and anisotropic, meaning that the velocity of light in the mineral depends on the path that it takes. In plane polarized light, uvite is colorless to pale yellow and shows weak pleochroism.[1]

Uvite was first found in 1929 in Uva Province, Sri Lanka, hence the name.[1]

Uvite has no use, but is commonly found in mineral specimen collections.[3] The mineral is sought after by collectors because of its pronounced colors, crystal structure, and often large crystal size.

References[edit]

  1. ^ a b c http://www.mindat.org/min-4126.html Mindat data
  2. ^ Darrell J. Henry, Milan Novák, Frank C. Hawthorne, Andreas Ertl, Barbara L. Dutrow, Pavel Uher, and Federico Pezzotta (2011). "Nomenclature of the tourmaline-supergroup minerals". American Mineralogist 96: 895–913. doi:10.2138/am.2011.3636. 
  3. ^ a b http://www.galleries.com/minerals/silicate/uvite/uvite.htm
  4. ^ http://webmineral.com/data/Uvite.shtml