Chrome-Tourmaline

Big Photo

Tanzania
5.75 carats
© Palagems

An intense green tourmaline which is colored by chromium and vanadium. The colour ranges from strong bluish green to very slightly yellowish green. At its best it can be compared to emerald.

It can be used as a lower-priced alternative to tsavorite garnet and emerald.

The main sources of the material are Kenya and Tanzania, but some fine chrome tourmalines are found in Myanmar.

Chrome-Tourmaline Gemstones by Colour

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

Chrome-Tourmaline Gemstones by Size

This table shows distribution of Chrome-Tourmaline 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:0.26 cts
Heaviest:5.75 cts
Average:0.90 cts
Total photos:18
Do you have a larger Chrome-Tourmaline? Why not upload a photo?
0.26ct to 0.81ct0.81ct to 1.36ct1.36ct to 1.91ct1.91ct to 2.46ct2.46ct to 3.01ct3.01ct to 3.55ct3.55ct to 4.10ct4.10ct to 4.65ct4.65ct to 5.20ct5.20ct to 5.75ct
General Information
A variety or type of:Tourmaline
Photos of natural/un-cut material from mindat.org
Physical Properties of Chrome-Tourmaline
Mohs Hardness7 to 7.5
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Specific Gravity2.85 to 3.35
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
TenacityBrittle
Michael O’Donoghue, Gems, Sixth Edition (2006)
Optical Properties of Chrome-Tourmaline
Refractive Index1.614 to 1.666
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Optical CharacterUniaxial/-
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Birefringence0.014 to 0.040
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
PleochroismStrong: dark green - yellow-green
Walter Schumann, Gemstones of the world (2001)
Colour
Colour (General)Fine emerald color
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) Possible green to (dark)-red color change
Colour (Chelsea Filter)Reddish
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Causes of ColourGreen due to chromium and/or vanadium.
CIBJO Coloured Stone Commission, The Gemstone Book (2012)
More from other references
TransparencyTransparent,Translucent,Opaque
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
LustreVitreous
Arthur Thomas, Gemstones (2009)
Fluorescence & other light emissions
Fluorescence (General)Weak to none
Walter Schumann, Gemstones of the world (2001)
Crystallography of Chrome-Tourmaline
Crystal SystemTrigonal
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
HabitLong crystals with triangular cross section and rounded sides, definite striation parallel to main axis
Walter Schumann, Gemstones of the world (2001)
Further Information
Mineral information:Chrome-Tourmaline information at mindat.org
Significant Gem Localities
Tanzania
 
  • Manyara Region
    • Simanjiro District
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