Rutile

Pale yellow, synthetic rutile may be turned an attractive blue color by heating at over 1000�C in a reducing atmosphere. Heating at 1000�C in oxygen reverses this change (Nassau, 1980) - Nassau (1984) Synthetic rutile: Colourless, yellowish, Transparent; Hardness 6 - 6.5; RI 2.616 - 2.903; Birefringence 0.287; Uniaxial/+; SG 4.26; Inclusions: occasionally gas bubbles - Gemmological Tables, Ulrich Henn and Claudio C. Milisenda, 2004, p 31 6 to 6.5Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references 4.20 to 4.30Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references DistinctUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) Sub-ConchoidalArthur Thomas, Gemstones (2009) 2.609 to 2.903Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references Uniaxial/+Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references 0.287Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) DoublingMore from other references StrongArthur Thomas, Gemstones (2009) Very highHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references Yes, star 4Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) (Dark) yellowish brown, reddish brown, blackHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references Blue (synthetic rutile), Band transition due to the presence of Ti3+W. William Hanneman, Pragmatic Spectroscopy For Gemologists (2011) Transparent,Translucent,OpaqueUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) Adamantine,MetallicMichael O?Donoghue, Gems, Sixth Edition (2006) InertHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) TetragonalHerve Nicolas Lazzarelli, Blue Chart Gem Identification (2010) More from other references slender prismatic striated lengthways, variably terminated and often geniculate twinned crystalsMichael O?Donoghue, Gems, Sixth Edition (2006) Rutile occurs as a common high-temperature, highpressure accessory mineral in igneous rocks and granite pegmatites and in regionally metamorphosed rocks including crystalline limestones. Rutile needles are common inclusions in a number of gem minerals.Michael O?Donoghue, Gems, Sixth Edition (2006) Rutile information at mindat.org Brazil  Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 445 Kyrgyzstan  Myanmar  Ted Themelis (2008) Gems & mines of Mogok Ted Themelis (2008) Gems & mines of Mogok Russia  Sri Lanka