Satin spar
Index of articles associated with the same name
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Satin spar, less commonly atlas spar, is a trivial, partly obsolete name for fibrous varieties of the minerals gypsum, calcite,[1]: 40 and aragonite.[2] Satin spars have a characteristic satin (silky) luster. Despite their very low hardness (2 or 3 on the Mohs scale), satin spars are widely used as ornamental stones.
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Spar is a general term for glassy, transparent to translucent minerals that cleave easily. Satin spars are not related to other minerals containing spar in their names, such as feldspar and fluorspar.[3]
Main minerals and varieties
- Satin spar gypsum is a white, fibrous variety of gypsum[4]: 217 that is sometimes called selenite.
- Satin spar calcite, or calcite spar, is a fibrous variety of calcite[5]: 429 that superficially resembles satin spar gypsum (selenite),[6]: 169 but is much less common in nature.
- Aragonite is one of the polymorphic varieties of calcite,[5]: 429 sometimes having the same satin effect.
