Milarite

Big Photo

Switzerland
0.20 carats

Milarite is named after its occurence in the Val Milar, Switzerland. The original specimens, however, came from Val Giuf, Tavetsch, Grischun, Switzerland.

Milarite is a rare beryllium silicate, that forms transparent to translucent colourless to pale yellow or green prismatic crystals, typically well formed.

A.Thomas (2009) reports: "The small pieces of facet rough that have been cut to date have all originated from a single African source".
General Information
Chemical Formula
KCa
 
2
AlBe
 
2
Si
 
12
O
 
30
· 0.5H
 
2
O
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
Photos of natural/un-cut material from mindat.org
Physical Properties of Milarite
Mohs Hardness5.5 to 6
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Specific Gravity2.52 to 2.60
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
TenacityBrittle
Arthur Thomas, Gemstones (2009)
Cleavage QualityImperfect
Arthur Thomas, Gemstones (2009)
FractureUneven,Conchoidal
Arthur Thomas, Gemstones (2009)
Optical Properties of Milarite
Refractive Index1.529 to 1.560
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Optical CharacterUniaxial/-
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Birefringence0.000 to 0.011
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
Colour
Colour (General)Yellow, colourless, white, green.
Walter Schumann, Gemstones of the world (2001)
More from other references
TransparencyTransparent
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
More from other references
LustreVitreous
Walter Schumann, Gemstones of the world (2001)
More from other references
Fluorescence & other light emissions
Fluorescence (General)Common weak to moderate chalky green (and phosphorescence)
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Crystallography of Milarite
Crystal SystemHexagonal
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
More from other references
HabitPrismatic crystals, typically well formed
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
Geological Environment
Where found:Milarite is found in vugs in granites and syenites or in hydrothermal veins.
Michael O’Donoghue, Gems, Sixth Edition (2006)
Inclusions in Milarite
May show thin elongated thread-like inclusions - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 7
Further Information
Mineral information:Milarite information at mindat.org
Significant Gem Localities
Brazil
 
  • Minas Gerais
    • Jaguaraçu
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 430
Copyright © Jolyon & Katya Ralph 1993-2019. Site Map. Locality, gem & photograph data are the copyright of the individuals who submitted them. For more information please contact the . Gemdat.org is an online information resource dedicated to providing free gemmological information to all.