Ettringite

Big Photo

South Africa
0.51 carats
© Mineral Classics

Ettringite is named after its discovery locality, at Ettringen, Eifel mts., Rheinland-Palatine, Germany.

Ettringite forms colourless to pale yellow transparent to opaque crystals, which can be faceted.
2 photos

Ettringite Gemstones by Colour

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

Ettringite Gemstones by Size

This table shows distribution of Ettringite 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:.42 cts
Heaviest:0.51 cts
Average:0.46 cts
Total photos:2
Do you have a larger Ettringite? Why not upload a photo?
0.42ct to 0.43ct0.43ct to 0.44ct0.44ct to 0.45ct0.45ct to 0.46ct0.46ct to 0.47ct0.47ct to 0.47ct0.47ct to 0.48ct0.48ct to 0.49ct0.49ct to 0.50ct0.50ct to 0.51ct
General Information
Chemical Formula
Ca
 
6
Al
 
2
(SO
 
4
)
 
3
(OH)
 
12
 26H
 
2
O
Michael O’Donoghue, Gems, Sixth Edition (2006)
Physical Properties of Ettringite
Mohs Hardness2 to 2.5
Michael O’Donoghue, Gems, Sixth Edition (2006)
Specific Gravity1.77
Michael O’Donoghue, Gems, Sixth Edition (2006)
Cleavage QualityPerfect
Michael O’Donoghue, Gems, Sixth Edition (2006)
Optical Properties of Ettringite
Refractive Index1.470 to 1.491
Michael O’Donoghue, Gems, Sixth Edition (2006)
Optical CharacterUniaxial/-
Michael O’Donoghue, Gems, Sixth Edition (2006)
Birefringence0.021
Michael O’Donoghue, Gems, Sixth Edition (2006)
Colour
Colour (General)Colourless to pale yellow
Michael O’Donoghue, Gems, Sixth Edition (2006)
TransparencyTransparent,Translucent,Opaque
Michael O’Donoghue, Gems, Sixth Edition (2006)
Crystallography of Ettringite
Crystal SystemHexagonal
Michael O’Donoghue, Gems, Sixth Edition (2006)
HabitPrismatic
Michael O’Donoghue, Gems, Sixth Edition (2006)
Geological Environment
Where found:Occurs in metamorphosed limestones near igneous contacts or in xenoliths
Michael O’Donoghue, Gems, Sixth Edition (2006)
Further Information
Mineral information:Ettringite information at mindat.org
Significant Gem Localities
South Africa
 
  • Northern Cape
    • John Taolo Gaetsewe District Municipality
      • Joe Morolong Local Municipality
        • N'Chwaning Mines
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 409
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 409
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