Satin Spar

In modern usage Satin Spar is a compact fibrous variety of Gypsum. It is generally white, silky and translucent with pearly or milky appearance.

Satin Spar can be cut into very striking chatoyant cabochons.

Historically, the name Satin Spar was first applied to a variety of calcite - see Calcite Satin Spar.
General Information
A variety or type of:Gypsum
Physical Properties of Satin Spar
Mohs Hardness2
Arthur Thomas, Gemstones (2009)
Specific Gravity1.52 to 1.53
Arthur Thomas, Gemstones (2009)
Optical Properties of Satin Spar
ChatoyancyChatoyant
Michael O’Donoghue, Gems, Sixth edition (2006)
Colour
Colour (General)White
Michael O’Donoghue, Gems, Sixth edition (2006)
LustreSilky,Pearly
Michael O’Donoghue, Gems, Sixth edition (2006)
Crystallography of Satin Spar
Crystal SystemMonoclinic
Arthur Thomas, Gemstones (2009)
HabitFibrous aggregates
Arthur Thomas, Gemstones (2009)
Geological Environment
Where found:Occurs filling veins in rock formations with parallel fibrous crystals stretching across the vein from side to side.
Michael O’Donoghue, Gems, Sixth edition (2006)
Further Information
Mineral information:Satin Spar information at mindat.org
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