තෝරමල්ලි

විකිපීඩියා, නිදහස් විශ්වකෝෂය වෙතින්
වෙත පනින්න: සංචලනය, සොයන්න
තෝරමල්ලි

Bi-colored tourmaline crystal, 0.8 inches (2 cm) long
General
Category Cyclosilicate
රසායනික සූත්‍රය (Ca,K,Na,[])(Al,Fe,Li,Mg,Mn)3(Al,Cr, Fe,V)6
(BO3)3(Si,Al,B)6O18(OH,F)4
[1][2]
Identification
පාට / පැහැය Most commonly black, but can range from brown, violet, green, pink, or in a dual-colored pink and green.
Crystal habit Parallel and elongated. Acicular prisms, sometimes radiating. Massive. Scattered grains (in granite).
Crystal system Trigonal
Cleavage Indistinct
Fracture Uneven, small conchoidal, brittle
Mohs scale hardness 7–7.5
Luster Vitreous, sometimes resinous
Streak White
Specific gravity 3.06 (+.20 -.06)[1]
ඝනත්‍වයy 2.82–3.32
Polish luster Vitreous[1]
Optical properties Double refractive, uniaxial negative[1]
Refractive index nω=1.635–1.675, nε=1.610–1.650
Birefringence -0.018 to -0.040; typically about .020 but in dark stones it may reach .040[1]
Pleochroism typically moderate to strong[1]
Red Tourmaline: Definite; dark red,light red
Green Tourmaline: Strong; dark green, yellow-green
Brown Tourmaline: Definite; dark brown, light brown
Blue Tourmaline: Strong; dark blue, light blue
Dispersion .017[1]
Ultraviolet fluorescence pink stones—inert to very weak red to violet in long and short wave[1]
Absorption spectra a strong narrow band at 498 nm, and almost complete absorption of red down to 640nm in blue and green stones; red and pink stones show lines at 458 and 451nm as well as a broad band in the green spectrum[1]


  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Gemological Institute of America, GIA Gem Reference Guide 1995, ISBN 0-87311-019-6
  2. Mindat tourmaline group Accessed September 12, 2005. This website details specifically and clearly how the complicated chemical formula is structured.
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