Mimetite

Big Photo

Chihuahua, Mexico
0.53 carats
© Rarestone.com

Mimetite is named from Greek "mimetes", an imitator, alluding to its resemblance to pyromorphite.

Mimetite forms transparent and very attractive prismatic crystals or botryoidal, globular masses of yellow to orange-yellow to brown colour, sometimes colourless with a characteristic resinous to subadamantine lustre.

Transparent, but slightly included material from Tsumeb has been faceted into gems over 1.00 ct (one specimen reported to show an orange-red fluorescence under LWUV).

Bright orange to pastel yellow and brown banded cabochons have been cut from globular masses of Mimetite from Mapimi, Durango, Mexico. Because of their high density and colour banding, these may be mistaken for the "wood tin" variety of cassiterite, or the "schalenblende" variety of sphalerite/wurtzite.

Mimetite Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
 
General Information
Chemical Formula
Pb
 
5
(AsO
 
4
)
 
3
Cl
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Photos of natural/un-cut material from mindat.org
Physical Properties of Mimetite
Mohs Hardness3.5
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Specific Gravity7.10
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Cleavage QualityImperfect
Arthur Thomas, Gemstones (2009)
FractureSub-Conchoidal
Arthur Thomas, Gemstones (2009)
Optical Properties of Mimetite
Refractive Index2.106 to 2.263
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Optical CharacterUniaxial/-
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Birefringence0.018 to 0.024
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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Colour
Colour (General)Orange, yellowish-orange, brownish
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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TransparencyTranslucent,Opaque
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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LustreSubadamantine,Resinous
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Crystallography of Mimetite
Crystal SystemHexagonal
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
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HabitPrismatic
Michael O’Donoghue, Gems, Sixth Edition (2006)
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Geological Environment
Where found:Mimetite occurs as a secondary mineral in the oxidized zone of arsenicbearing lead deposits.
Michael O’Donoghue, Gems, Sixth Edition (2006)
Further Information
Mineral information:Mimetite information at mindat.org
Significant Gem Localities
Mexico
 
  • Durango
    • Mun. de Mapimí
Namibia
 
  • Oshikoto Region
    • Tsumeb
Gems, Sixth Edition, Michael O’Donoghue, 2006, p. 430
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