Gypsum Value, Price, and Jewelry Information


Gypsum
Gypsum with sulphur Locality: Cianciana, Agrigento Province, Sicily, Italy Size :32 x 18 x 10 cm By Didier Descouens (Own work) [GFDL or CC-BY-SA-3.0-2.5-2.0-1.0], via Wikimedia Commons

Gypsum is one of the most abundant minerals and is found especially in evaporite environments. Alabaster, the massive, granular variety, has been used for thousands of years, made into vases, bowls, and other useful and decorative objects. Today it is used in ashtrays, clock housings, paperweights, and so forth.

Gypsum Value

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Gypsum Information

DataValue
NameGypsum
VarietiesAlabaster, Satin Spar, Selenite
Alternate Common NamesAlso known as Alabaster, a variety of Satin Spar
Crystallography Monoclinic. Crystals often perfect and large; tabular; rosettes; lenticular; helictites are grotesque shapes found in caves; often twinned; massive; granular.
Colors Colorless, white, gray; impurities make it yellowish, reddish, brownish, greenish. Sometimes banded and patterned like marble.
Luster Subvitreous; pearly on cleavages.
Polish Luster Waxy to subvitreous
Fracture Luster Dull to pearly
Fracture Granular
Hardness 2
Toughness Poor
Specific Gravity 2.32 (range 2.30-2.33)
Birefringence 0.010
Cleavage Perfect and easy, 1 direction; distinct 2 other directions.
Dispersion 0.033
Stone SizesMassive gypsum in any desired size (for cabochons and carvings). Fibrous material cut into large carvings, up to several pounds. Faceted gypsum could be up to hundreds of carats, as large transparent crystals exist.
Luminescence Sometimes indistinct brownish or greenish white in UV. Inert in X-rays.
Spectral Not diagnostic
Enhancements Dyeing, common. Bleaching, common. Occasional heating to improve color, prepare for dying.
Transparency Translucent to Opaque
UV LongInert to weak brownish to greenish white
UV ShortInert to weak brownish to greenish white
Absorption Spectrum Not diagnostic
Phenomena Chatoyant
FormulaCaSO4 2H2O.
Pleochroism None

Opticsa = 1.520; β= 1.523;  γ= 1.530.

Biaxial (+), 2V= 58°.

Occurrence: In sedimentary rocks and deposits; saline lakes; oxidized parts of ore deposits; volcanic deposits. Utah; Michigan; Colorado; South Dakota; New Mexico; New York; Kansas; other states.

California: many locations.

Mexico: at Naica, Chihuahua, in enormous crystals to 6 feet long.

Braden, Chile: crystals reported up to 10 feet long. Alabaster from England; Tuscany, Italy

Comments: Gypsum is one of the most abundant minerals and is found especially in evaporite environments. Alabaster, the massive, granular variety, has been used for thousands of years, made into vases, bowls, and other useful and decorative objects. Today it is used in ashtrays, clock housings, paperweights, and so forth.

Gypsum can be scratched by the fingernail, so it is much too soft for hard use. Care must be taken in handling carvings and useful objects, but scratches can be polished out rather easily.

Selenite is the term applied to colorless, transparent crystals. Satin spar is used to describe massive fibrous varieties that are often cut into cabochons or carved into animal shapes. This material has a great chatoyancy, and brown-colored satin spar makes lovely decorative items. Faceted gypsum is not often seen since cut stones are unattractive and very difficult to fashion, due to the exceptionally perfect cleavage and low hardness of the material.

Name: Gypsum from the Greek gypsos, a name applied to what we now call plaster. Satin spar in allusion to the satiny luster of the fibrous material. Selenite from the Greek word for moon, due to the pearly luster on cleavage surfaces. Alabaster f tom the Greek word alabastros, a stone from which ointment vases were made.

Variety Names: Also known as Alabaster. Selenite transparent, colorless gypsum.

Trade Names: Satinspar fibrous gypsum.