SCHEELITE

CaWO₄ 
Tetragonal

Scheelite, a calcium tungstate mineral and the tungsten analogue of powellite, is less common than powellite locally; it has veen verified in only one assemblage from Franklin, and probable scheelite was subsequently found at Sterling Hill. 

At Franklin, scheelite occurs as isolated, anhedral crystals up to 1 cm; some are arranged linearly in a band in the observed specimens. This scheelite is subtranslucent, colorless to light gray, and has a resinous to adamantine luster. It is fluorescent in ultraviolet with a moderate yellow color in shortwave ultraviolet and a weaker yellow in longwave. Semiquantitative analysis shows it to have a composition of approximately CaO 20 wt.%, WO₃ 66 wt. %, and MoO₃ 12 wt. % and thus to contain approximately 75 mole % scheelite. The material described above was found near the Trotter Shaft, in a dark-colored matrix, associated with fluorapatite, pyroxmangite, microcline, willemite, and calcite. Scheelite was also found associated with secondary willemite and franklinite from Franklin.  

At Sterling Hill, probable scheelite was found occurring in colorless 0.3-1.0 mm crystals associated with secondary epidote, manganaxinite, fluorite, and calcite just above the 1300 level. This probable scheelite has not been analyzed; it has a vivid bright blue fluorescence response color in ultraviolet. Unanalyzed material in the scheelite-powellite series was found associated with scapolite, a Ca-As apatite, and green-fluorescent chabazite on the 340 level in 1990.

Copyright © 1995 by Pete J. Dunn			Website by Herb Yeates
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This page created: January 11, 2001