Chrome-Tourmaline

Tanzania
1.12 carats
© Palagems

A rare intense green tourmaline is known as chrome tourmaline. Found only in East Africa, it is colored by chromium and vanadium.

9 photos

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:0.34 cts

Heaviest:5.75 cts

Average:1.40 cts

Total photos:9

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0.34ct to 0.88ct0.88ct to 1.42ct1.42ct to 1.96ct1.96ct to 2.50ct2.50ct to 3.05ct3.05ct to 3.59ct3.59ct to 4.13ct4.13ct to 4.67ct4.67ct to 5.21ct5.21ct to 5.75ct

General Information
A variety or type of:	Tourmaline
Physical Properties of Chrome-Tourmaline
Mohs Hardness	7 to 7.5 Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Specific Gravity	2.85 to 3.35 Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Tenacity	Brittle Michael O�Donoghue, Gems, Sixth Edition (2006)
Optical Properties of Chrome-Tourmaline
Refractive Index	1.614 to 1.666 Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Optical Character	Uniaxial/- Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Birefringence	0.014 to 0.040 Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Pleochroism	Strong: 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 Colour	Green ("chrome tourmaline"), V³⁺ generally with minor amounts of Cr³⁺, both in octahedral coordination. W. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011) More from other references
Transparency	Transparent,Translucent,Opaque Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Lustre	Vitreous 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 System	Trigonal Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Habit	Long 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

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