USA
9.98 carats
© gemselect.com
General Information | ||||||||||||||||||
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Chemical Formula |
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Howlite Treatments | ||||||||||||||||||
Howlite has been dyed various colors and may also be waxed. An elaborate carving was dyed blue to produce a superficial resemblance to turquoise; a test used to identify it was to etch the surface with acid and observe melting of the howlite with a hot needle (Crowningshield, 1969) – Nassau (1984) Dyed blue to imitate turquoise (and lapis lazuli). Acetone test may reveal the dye - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 5 | ||||||||||||||||||
Physical Properties of Howlite | ||||||||||||||||||
Mohs Hardness | 3 to 3.5Blue Chart Gem Identification (2010) , More from other references | |||||||||||||||||
Specific Gravity | 2.45 to 2.58Blue Chart Gem Identification (2010) , More from other references | |||||||||||||||||
Cleavage Quality | NoneGemstones (2009) , | |||||||||||||||||
Fracture | UnevenGemstones (2009) , | |||||||||||||||||
Optical Properties of Howlite | ||||||||||||||||||
Refractive Index | 1.583 to 1.608Blue Chart Gem Identification (2010) , More from other references | |||||||||||||||||
Optical Character | Biaxial/-Gemmological Tables (2004) , More from other references | |||||||||||||||||
Birefringence | 0.019Gemmological Tables (2004) , More from other references | |||||||||||||||||
Pleochroism | NilGemstones (2009) , | |||||||||||||||||
Dispersion | NilGemstones (2009) , | |||||||||||||||||
Colour | ||||||||||||||||||
Colour (General) | Natural color: white, commonly with gray to black "spiderweb" matrix.Blue Chart Gem Identification (2010) , More from other references | |||||||||||||||||
Colour (Chelsea Filter) | Dyed howlite: pink to redBlue Chart Gem Identification (2010) , | |||||||||||||||||
Causes of Colour | Blue, dyes exclusivelyPragmatic Spectroscopy For Gemologists (2011) , | |||||||||||||||||
Transparency | OpaqueGemmological Tables (2004) , More from other references | |||||||||||||||||
Lustre | Vitreous,Dull (Earthy)Gemstones (2009) , sub-vitreous | |||||||||||||||||
Fluorescence & other light emissions | ||||||||||||||||||
Fluorescence (Short Wave UV) | Occasionally orangeGemmological Tables (2004) , More from other references | |||||||||||||||||
Fluorescence (Long-Wave UV) | Brownish-yellowGemmological Tables (2004) , More from other references | |||||||||||||||||
Crystallography of Howlite | ||||||||||||||||||
Crystal System | MonoclinicBlue Chart Gem Identification (2010) , More from other references | |||||||||||||||||
Habit | TabularGems, Sixth Edition (2006) , More from other references | |||||||||||||||||
Geological Environment | ||||||||||||||||||
Where found: | Howlite is found in borate deposits.Gems, Sixth Edition (2006) , | |||||||||||||||||
Further Information | ||||||||||||||||||
Mineral information: | Howlite information at mindat.org |