http://www.all-gemstones.com www.all-gemstones.com    Thu, 06 May 2010 12:29:47 +0000 http://wordpress.org/?v=2.8.6 en hourly 1 http://www.all-gemstones.com/uvite http://www.all-gemstones.com/uvite#comments Tue, 18 Aug 2009 06:15:28 +0000 admin http://www.all-gemstones.com/?p=1450   Refractive Index : 1.660 – 1.612 Optical Characteristic : DR, Uniaxial negative Specific Gravity : 3.06 (- 0.20 – 0.06) Formula : CaMg3(AI5Mg)BSi6O27(OH)3(OH,f) Crystal System : Trigonal Variety/Species : Tourmaline Species/Group : Tourmaline Group Birefringence : 0.017 to 0.021 Dispersion : 0.017 Hardness : 7 to 7.5 Toughness : Fair Ultrasonic : Risky Steam : Risky UV Long : Inert to weak UV Short : Inert to weak Pleochroism : 2 colors Strength : Weak to strong

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Pleochroism Colors : Moderate to strong. Generally light and dark tones of body colors. Heat : May fracture or change color Acids : No reaction Light : Stable Polish Luster : Vitreous Fracture : Conchoidal Fracture Luster : Vitreous Clarity Type : I to III Tones : N/A Saturations : N/A Cause of Color : Pink-manganese Enhancements : Heating, Irradiation, acid treatment Cleavage : None Color Range : Brown, black, green, blackish brown, brownish black, usuallly dark colored Transparency : Transparent to opaque Phenomena : Color change (rare), aventurescence, chatoyancy

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Separations : Uvite from-
Natural Topaz : birefringence, optic character, SG, cleavage, spectrum(possibly)Andalusite : Birefringence, optic character, pleochroism, spectrum Identifying Characteristics and information
thread-like liquid and gas inclusions,gas filled fractures.
Birefringence is usually 0.018 – 0.020 but in dark stones it may be as high as 0.040. Spectral Data
Not diagnostic. Weak spectra usually observed Trade Names and Misnomers
Uvite   ]]> http://www.all-gemstones.com/uvite/feed 0 http://www.all-gemstones.com/vanadiumdravite http://www.all-gemstones.com/vanadiumdravite#comments Sat, 15 Aug 2009 04:51:59 +0000 admin http://www.all-gemstones.com/?p=1456   Refractive Index : 1.786 – 1.729 Optical Characteristic : DR, uniaxial negative Specific Gravity : 3.32 Formula : NaMg3V6(Si6O18)(BO3)3(OH)4 Crystal System : Trigonal Variety/Species : Tourmaline Species/Group : Tourmaline Group Birefringence : 0.057 Dispersion : 0.017 Hardness : 7.5 Toughness : Fair Ultrasonic : Risky Steam : Risky UV Long : Inert UV Short : Inert Pleochroism : 2 colors Strength : Moderate to strong

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Pleochroism Colors : No data Heat : May fracture or change color Acids : No reaction Light : Stable Polish Luster : Resinuous Fracture : Fracture Luster : Clarity Type : N/A Tones : N/A Saturations : N/A Cause of Color : N/A Enhancements : None Cleavage : None Color Range : Dark green, green, black greenish, blackish Transparency : Translucent to opaque Phenomena : None

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Separations : Vanadiumdravite from- Identifying Characteristics and information
Thread-like liquid and gas inclusions, gas filled fractures.Vanadiumdravite is a very rare stone and not often seen as a gem. Spectral Data
Not diagnostic Trade Names and Misnomers
Vanadiumdravite   ]]> http://www.all-gemstones.com/vanadiumdravite/feed 0