Pleonaste

Big Photo

Mexico
7.63 carats
© Rarestone.com

Pleonaste is named from the greek word for 'abundant' due to its numerous crystal forms.

Pleonaste is an opaque, dark blue or green to black variety of Spinel containing iron.

Pleonaste Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
 
General Information
A variety or type of:Spinel
Chemical Formula
(Mg,Fe)Al
 
2
O
 
4
Gemdat.org, Management Team (2012)
Photos of natural/un-cut material from mindat.org
Physical Properties of Pleonaste
Mohs Hardness8
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Specific Gravity3.80
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Cleavage QualityNone
Michael O’Donoghue, Gems, Sixth Edition (2006)
Optical Properties of Pleonaste
Refractive Index1.780
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Optical CharacterIsotropic
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Colour
Colour (General)Black
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
TransparencyOpaque
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
LustreVitreous
Arthur Thomas, Gemstones (2009)
Crystallography of Pleonaste
Crystal SystemIsometric
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
HabitOctahedra though some specimens may show dodecahedron or cube faces.
Michael O’Donoghue, Gems, Sixth Edition (2006)
Further Information
Mineral information:Pleonaste information at mindat.org
Significant Gem Localities
Madagascar
 
  • Anosy
Pezzotta (1999)
Sri Lanka
 
  • Sabaragamuwa Province
    • Ratnapura District
      • Ratnapura
Thailand
 
  • Kanchanaburi Province
    • Bo Phloi District
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