August Mineral of the Month – Sphalerite

Sphalerite

Sphalerite

Formula: ZnS, (zinc sulfide)
Colour: Yellow, light to dark brown, black, red-brown, colourless, light blue. green
Lustre: Adamantine, Resinous
Hardness: 3½ – 4
Specific Gravity: 3.9 – 4.1
Crystal System: Isometric
Member of: Sphalerite Group
Name: Named in 1847 by Ernst Friedrich Glocker from the Greek σφαλεροζ “sphaleros” = treacherous, in allusion to the ease with which dark varieties were mistaken for galena, but yielded no lead. Originally called blende in 1546 by Georgius Agricola (Georg Bauer). Known by a variety of chemical-based names subsequent to Agricola and before Glocker, including “zincum”. Sphalerite, also known as blende or zinc blende, is the major ore of zinc.
Dimorph of: Wurtzite
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