Dravite

Color may be improved or created by irradiation of colorless to light colored stones (not detectable) - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 5 7Anthony et al, Handbook of mineralogy (2001) 3.03 to 3.18Anthony et al, Handbook of mineralogy (2001) BrittleAnthony et al, Handbook of mineralogy (2001) PoorAnthony et al, Handbook of mineralogy (2001) Very poor Uneven,Irregular,ConchoidalAnthony et al, Handbook of mineralogy (2001) 1.614 to 1.666Walter Schumann, Gemstones of the world (2001) Uniaxial/-Anthony et al, Handbook of mineralogy (2001) 0.014 to 0.032Walter Schumann, Gemstones of the world (2001) 0.017Walter Schumann, Gemstones of the world (2001) Yellow brown to orangyHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) Not always dravite species!More from other references Yellow to brown, related to titanium; due to Fe2+-O-Ti4+ charge transfer, with those low in iron yellow and those rich in iron brown. Red, Fe3+ pairs.W. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011) Transparent,TranslucentAnthony et al, Handbook of mineralogy (2001) Vitreous,ResinousAnthony et al, Handbook of mineralogy (2001) May weakly fluoresceAnthony et al, Handbook of mineralogy (2001) HexagonalAnthony et al, Handbook of mineralogy (2001) Crystals equant or short to long prismatic, with dominant pyramid faces, to 20 cm. Striated, cross sections typically triangular with curved convex sides. Commonly radiating, granular, and massive.Anthony et al, Handbook of mineralogy (2001) Commonly in metamorphosed limestones or mafic igneous rocks with metasomatically introduced boron; rarely in pegmatites; as authigenic overgrowths in sedimentary rocks.Anthony et al, Handbook of mineralogy (2001) Dravite information at mindat.org Myanmar  Ted Themelis (2008) Gems & mines of Mogok Ted Themelis (2008) Gems & mines of Mogok Ted Themelis (2008) Gems & mines of Mogok Sri Lanka