Achroite - A colourless variety of Tourmaline
Chrome-Tourmaline - An emerald-green variety of tourmaline.
Dravite - A sodium magnesium aluminium tourmaline species.
Elbaite - A sodium lithium aluminium tourmaline species.
Cuprian Elbaite - A copper-bearing Elbaite.
Fluor-uvite-Uvite Series - A calcium magnesium aluminium tourmaline species.
Indicolite - A blue gemmy variety of tourmaline (usually
Liddicoatite - A calcium lithium tourmaline species.
Rubellite - A pink to red gem variety of tourmaline.
Schorl - A sodium iron aluminium tourmaline species.
Verdelite - A green gem variety of tourmaline
Watermelon Tourmaline - A variety of Tourmaline with colour zoning showing a pink core and green edges.
|Photos of natural/un-cut material from mindat.org|
|By heating to 842 - 1202 degrees F (450 - 650 degrees C), color changes can be produced in some tourmalines. Some green tourmaline becomes emerald green; other are lightened. The color of tourmalines which have been changed with gamma-irradiation may fade. - Gemstones of the world, Walter Schumann, 200, p 112|
Coatings on tourmaline give wide range of options for colour, iridescence and other appearance factors.The coating are shallow and can be easily damaged without proper handling. - GIA, 2018
|Synthetic tourmalines are used only for research purposes. The stones, offered as synthetic tourmaline, are rarely tourmaline-colored synthetic spinels. - Gemstones of the world, Walter Schumann, 2001, p 112|
|Physical Properties of Tourmaline|
|Mohs Hardness||7 to 7.5Blue Chart Gem Identification (2010) , More from other references|
|Specific Gravity||2.85 to 3.35Blue Chart Gem Identification (2010) , More from other references|
|Tenacity||BrittleGems, Sixth Edition (2006) ,|
|Cleavage Quality||PoorGems, Sixth Edition (2006) , Very poorMore from other references|
|Fracture||Sub-ConchoidalGemstones (2009) ,|
|Optical Properties of Tourmaline|
|Refractive Index||1.614 to 1.666Blue Chart Gem Identification (2010) , More from other references|
|Optical Character||Uniaxial/-Blue Chart Gem Identification (2010) , More from other references|
|Birefringence||0.014 to 0.040Blue Chart Gem Identification (2010) , More from other references|
|Pleochroism||Pink tourmaline - distinct: colorless-pink - pinkish-red; Orange/brown tourmaline - strong: yellowish-brown - dark(greenish)-brown; Yellow tourmaline - distinct: pale yellow - dark yellow; Violet/purple tourmaline - strong: light purple - purple; Blue - strong: light blue - dark blue; Green - strong: yellow-green - dark greenBlue Chart Gem Identification (2010) , More from other references|
|Dispersion||0.017Gemstones (2009) ,|
|Chatoyancy||Tourmaline cat's eyes exist in various colors, but only in the green and pink varieties. Chatoyancy is usually strong, caused by thin tube-like inclusions. Some tourmalines show a slight change of color in artificial light. They have a vitreous sheen ob crystal surfaces, a greasy sheen on fractured surfaces.Gemstones of the world (2001) , More from other references|
|Colour (General)||Multi-colored crystals are commonBlue Chart Gem Identification (2010) , More from other references|
|Transparency||Transparent,Translucent,OpaqueGemmological Tables (2004) , More from other references|
|Lustre||VitreousGemstones (2009) ,|
|Fluorescence & other light emissions|
|Fluorescence (General)||Mostly inertBlue Chart Gem Identification (2010) ,|
|Crystallography of Tourmaline|
|Crystal System||TrigonalBlue Chart Gem Identification (2010) , More from other references|
|Habit||Prismatic to acicular crystalsGems, Sixth Edition (2006) , More from other references|
|Inclusions in Tourmaline|
|Thread of fiber-like capillaries often plaited in net-like pattern. Angular thin film mirror-like inclusions. Tube-like 2 phase inclusions running parallel to crystal's length: may create chatoyancy - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 5|
Flat, film-like liquid inclusions, parallel oriented hollow tubes, needle-like mineral inclusions - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 14
|Mineral information:||Tourmaline information at mindat.org|
|Significant Gem Localities|