Powellite

Big Photo

India
0.80 carats
© Rarestone.com

Powellite is named after Major J.W. Powell, American explorer, geologist and ethnologist.

Powellite forms transparent to translucent colourless, straw yellow, greenish yellow, greenish blue or blue crystals with characteristically greasy or subadamantine lustre.

Facetable material is rare as crystals are usually small and seldom exceed 2 carats.

Powellite Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
 
 

Powellite Gemstones by Size

This table shows distribution of Powellite gemstone sizes that are listed on this site. This can give a good indication as to the general availability of this gemstone in different sizes.
Contributed photos
Lightest:0.80 cts
Heaviest:5.09 cts
Average:2.06 cts
Total photos:4
Do you have a larger Powellite? Why not upload a photo?
0.80ct to 1.23ct1.23ct to 1.66ct1.66ct to 2.09ct2.09ct to 2.52ct2.52ct to 2.95ct2.95ct to 3.37ct3.37ct to 3.80ct3.80ct to 4.23ct4.23ct to 4.66ct4.66ct to 5.09ct
General Information
Chemical Formula
CaMoO
 
4
Michael O’Donoghue, Gems, Sixth Edition (2006)
Photos of natural/un-cut material from mindat.org
Physical Properties of Powellite
Mohs Hardness3.5 to 4
Michael O’Donoghue, Gems, Sixth Edition (2006)
Specific Gravity4.23
Michael O’Donoghue, Gems, Sixth Edition (2006) Near 4.23
Cleavage QualityIndistinct
Anthony et al, Handbook of Mineralogy (2001)
FractureUneven
Anthony et al, Handbook of Mineralogy (2001)
Optical Properties of Powellite
Refractive Index1.974 to 1.984
Michael O’Donoghue, Gems, Sixth Edition (2006)
Optical CharacterUniaxial/+
Michael O’Donoghue, Gems, Sixth Edition (2006)
PleochroismIn deeply colored specimens: blue - green
Anthony et al, Handbook of Mineralogy (2001)
Colour
Colour (General)Straw yellow, greenish yellow, greenish blue or blue
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
TransparencyTransparent,Translucent
Michael O’Donoghue, Gems, Sixth Edition (2006)
LustreSubadamantine,Greasy
Michael O’Donoghue, Gems, Sixth Edition (2006)
Fluorescence & other light emissions
Fluorescence (General)Specimens may fluoresce yellowish white to
golden yellow
Michael O’Donoghue, Gems, Sixth Edition (2006)
Fluorescence (Short Wave UV)Fluoresces creamy white or yellow to golden yellow
Anthony et al, Handbook of Mineralogy (2001)
Crystallography of Powellite
Crystal SystemTetragonal
Michael O’Donoghue, Gems, Sixth Edition (2006)
HabitDipyramidal crystals
Michael O’Donoghue, Gems, Sixth Edition (2006)
More from other references
Geological Environment
Where found:Powellite occurs as an uncommon secondary mineral in the oxidation zone of molybdenum-bearing hydrothermal mineral
deposits.
Michael O’Donoghue, Gems, Sixth Edition (2006)
Further Information
Mineral information:Powellite information at mindat.org
Significant Gem Localities
India
 
  • Maharashtra
    • Nashik District
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 440
USA
 
  • Michigan
    • Houghton Co.
      • Calumet Township
        • Calumet
          • Calumet & Hecla Mine
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 439
      • Houghton
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 439
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