Gypsum

Gypsum is named from Greek "gypsos" - plaster, alluding to its practical use. It has been known from antiquity.

Gypsum is a very common mineral in sedimentary environments. It is found as massive material (Alabaster), clear crystals (Selenite) and parallel fibrous variety (Satin spar).

Gypsum is very soft and very difficult to facet because of its perfect cleavage, therefore faceted stones are quite rare.

Gypsum Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
 

Gypsum Gemstones by Size

This table shows distribution of Gypsum gemstone sizes that are listed on this site. This can give a good indication as to the general availability of this gemstone in different sizes.
Contributed photos
Lightest:1.90 cts
Heaviest:8.26 cts
Average:5.08 cts
Total photos:2
Do you have a larger Gypsum? Why not upload a photo?
1.90ct to 2.54ct2.54ct to 3.17ct3.17ct to 3.81ct3.81ct to 4.44ct4.44ct to 5.08ct5.08ct to 5.72ct5.72ct to 6.35ct6.35ct to 6.99ct6.99ct to 7.62ct7.62ct to 8.26ct
General Information
Varieties/Types:
Alabaster - A fine-grained massive form of Gypsum.
Satin Spar - A fibrous variety of Gypsum.
Selenite - Transparent, colourless variety of Gypsum.
Chemical Formula
CaSO
 
4
-2(H
 
2
O)
Arthur Thomas, Gemstones (2009)
Photos of natural/un-cut material from mindat.org
Physical Properties of Gypsum
Mohs Hardness2
Walter Schumann, Gemstones of the world (2001)
More from other references
Specific Gravity2.20 to 2.40
Walter Schumann, Gemstones of the world (2001)
More from other references
Cleavage QualityPerfect
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
More from other references
FractureUneven
Arthur Thomas, Gemstones (2009)
Heat SensitivityVery sensitive
Walter Schumann, Gemstones of the world (2001)
Optical Properties of Gypsum
Refractive Index1.521 to 1.531
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
More from other references
Optical CharacterBiaxial/+
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
More from other references
Birefringence0.010
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
More from other references
PleochroismNil
Arthur Thomas, Gemstones (2009)
DispersionNil
Arthur Thomas, Gemstones (2009)
ChatoyancyYes
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Colour
Colour (General)White, yellowish, colourless, pink, bluish.
Walter Schumann, Gemstones of the world (2001)
More from other references
TransparencyTransparent,Translucent,Opaque
Walter Schumann, Gemstones of the world (2001)
More from other references
LustreVitreous,Silky
Walter Schumann, Gemstones of the world (2001) Fibrous aggregates have silky lustreMore from other references
Crystallography of Gypsum
Crystal SystemMonoclinic
Walter Schumann, Gemstones of the world (2001)
More from other references
HabitTabular
Arthur Thomas, Gemstones (2009)
Further Information
Mineral information:Gypsum information at mindat.org
Significant Gem Localities
Czech Republic
 
  • Ústí Region
    • Žatec (Saaz)
Italy
 
  • Tuscany
    • Pisa Province
      • Castellina Marittima
        • Marmolaio Valley
          • Pomaia
[var: Alabaster] Gems, Sixth Edition, Michael O’Donoghue , 2006, p. 378
Peru
 
  • Amazonas
[var: Alabaster]
  • Huancavelica
    • Castrovirreyna Province
  • Ica
    • Pisco Province
      • Pisco
        • Paracas
          • Otuma village
    • Pisco Umay
  • Lima
    • Cajatambo Province
UK
 
  • England
    • Derby
[var: Alabaster] Gems, Sixth Edition, Michael O’Donoghue , 2006, p. 379
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