Powellite


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powellite

[‚pau̇·ə‚līt]
(mineralogy)
Ca(WMo)O4 A commercially important tungsten mineral, crystallizing in the tetragonal system; isomorphous with scheelite (CaWO4).

Powellite

 

(named after the American geologist J. Powell), a mineral, calcium molybdate (CaMoO4). Powellite contains 28.48 percent CaO and 71.52 percent M0O3; some varieties contain up to 10.3 percent WO3. The mineral crystallizes in the tetragonal system. Sometimes it is found in the form of small crystals of a lamellar or dipyramidal habit. Most often it forms cryptocrystalline aggregates—products of alteration of molybdenite—which sometimes preserve the foliated structure typical of molybdenite. Its color ranges from white to dark green and brown. Powellite has a hardness of 3.5 on Mohs’ scale and a density of 4,250–4,520kg/m3. In ultraviolet light a yellow luminescence is usually detected. Powellite is a characteristic mineral of the oxidized zone of the ores of molybdenum deposits.

References in periodicals archive ?
On the basis of Powellite doctrine we should welcome today's immigrants, since they dilute even further the non-white presence here.
powellite, cobaltlotharmeyerite, cobaltaustinite, cobaltarthurite and guanacoite, as well as interesting varieties of cobaltaustinite and zinc-rich roselite-beta.
Accessory minerals are biotite, calcite, cassiterite, chalcopyrite, chlorite, ferberite, goethite, titanite, zircon, bismuth, powellite, scheelite and minor sulfides such as arsenopyrite, pyrite and molybdenite (Schlogl, 1984).
It is in fact a return to the Powellite anti-immigration agenda.
If he does so in future, I hope he brings more of the new crystals of powellite which he had in France; these were found, he says, in early 2006 in a well-digging at Jamner, near Jalgaon, in India's zeolite-bearing Deccan Plateau.
They flagged me down and showed me several fine new specimens of powellite, one having a mirror-bright, doubly terminated powellite crystal 2.
Among them were Lord Biffen, with whom there had sometimes been political differences, and Mr Nicholas Budgen, who had often been outspoken in his support of Powellite immigration theory, and his former Unionist Party leader in Northern Ireland, Mr JamesMolyneux.
The Aurangabad site also yielded about 500 fair-to-good specimens of powellite, with translucent white to pale orange, rounded clusters of powellite "points" to 8 cm across with the stilbite.
Arvind Bhale of Earth Science International ('Yasham,' 166/1+2+3, Aundh Gaon, Pune-411007, India), who had about 30 specimens, from toenail through cabinet size, of celadonite-infused powellite found in 2001 at Shakur, Maharashtra state.
Now, where's that powellite specimen you talked about over the phone?
And (5) molybdenite, powellite and ore specimens from the Jardinera #1 Mine near Inca de Oro that supplement material previously acquired for the description of szencisite.
Szenicsite joins ferrimolybdite, lindgrenite, powellite and wulfenite as a simple molybdate.