Danalite

Danalite
General
Category Sodalite - Feldspathoid
Formula
(repeating unit)		 Fe2+4Be3(SiO4)3S
Strunz classification 09.FB.10
Dana classification 76.02.04.02
Identification
Color Yellow, pink, reddish brown, red: colorless to pink in thin section
Crystal habit Octahedral and dodecahedral crystals, typically massive or as segregations
Crystal system Isometric - hextetrahedral (4 3m)
Cleavage {111} and {111}
Fracture Subconchoidal to uneven
Tenacity Brittle
Mohs scale hardness 5.5 to 6
Luster Vitreous or greasy
Streak Grey white
Diaphaneity Semitransparent
Specific gravity 3.28 - 3.46
Optical properties Isotropic
Refractive index n = 1.747 - 1.771
References [1][2][3]

Danalite is an iron beryllium silicate sulfide mineral with formula: Fe2+4Be3(SiO4)3S.

It is a rare mineral which occurs in granites, tin bearing pegmatites, contact metamorphic skarns, gneisses and in hydrothermal deposits. It occurs in association with magnetite, garnet, fluorite, albite, cassiterite, pyrite, muscovite, arsenopyrite, quartz, and chlorite.[1]

Danalite was first described in 1866 from a deposit in Essex County, Massachusetts and named for American mineralogist James Dwight Dana (1813–1895).[3]

It has been found in Massachusetts, New Hampshire, Sierra County, New Mexico; Yavapai County, Arizona; Needlepoint Mountain, British Columbia; Walrus Island, James Bay, Quebec; Sweden; Cornwall, England; Imalka and Transbaikal, Russia; Kazakhstan; Somalia; Tasmania; Western Australia and Hiroshima Prefecture, Japan.[1][2]

References

  1. 1 2 3 http://rruff.geo.arizona.edu/doclib/hom/danalite.pdf Handbook of Mineralogy
  2. 1 2 http://www.mindat.org/min-1341.html Mindat.org
  3. 1 2 http://webmineral.com/data/Danalite.shtml Webmineral data
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