Satin spar

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.

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.

See also

References

  1. ^ Krivovichev V. G. Mineralogical glossary. Scientific editor A. G. Bulakh. — St.Petersburg: St.Petersburg Univ. Publ. House. 2009. — 556 p. — ISBN 978-5-288-04863-0. (in Russian)
  2. ^ "Satin Spar". mindat.org. Hudson Institute of Mineralogy. Retrieved 7 October 2025.
  3. ^ "Definition of spar". mindat.org. Hudson Institute of Mineralogy. Retrieved 7 October 2025.
  4. ^ R. A. Lidin, L. L. Andreeva, V. A. Molochko. Constants of inorganic substances: handbook. 3rd ed., reprinted, edited by R. A. Lidin. — Москва: Дрофа, 2008 г. — 685 с. (in Russian)
  5. ^ a b G. F. Herbert Smith. Gemstones. 14th ed., reviewed by F. C. Phillips. — London, Chapman & Hall, 1972. — 580 p. ISBN 0412108909
  6. ^ Boris Cantor. Collecting Minerals. 2nd edition, revised and enlarged. — Moscow: Nedra, 1991. — 173 p. (in Russian)
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