Danalite

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Danalite
Danalite-202027.jpg
General
CategorySodalite - Feldspathoid
Formula
(repeating unit)
Fe2+4Be3(SiO4)3S
Strunz classification9.FB.10
Dana classification76.02.04.02
Crystal systemIsometric
Crystal classHextetrahedral (43m)
H-M symbol: (4 3m)
Space groupP43n
Identification
ColorYellow, pink, reddish brown, red: colorless to pink in thin section
Crystal habitOctahedral and dodecahedral crystals, typically massive or as segregations
Cleavage{111} and {111}
FractureSubconchoidal to uneven
TenacityBrittle
Mohs scale hardness5.5 to 6
LusterVitreous or greasy
StreakGrey white
DiaphaneitySemitransparent
Specific gravity3.28 - 3.46
Optical propertiesIsotropic
Refractive indexn = 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[edit]