DescriptionFINE AND MASSIVE FLUORESCENT POWELLITE
Tierra Amarilla, southern Atacama Desert, Chile
Powellite is a Calcium Molybdate mineral: isomorphous with Scheelite, but much rarer as a display-quality fluorescent mineral. It usually occurs as a weathering product of Molybdenite: the main ore of Molybdenum, but it is seldom showy enough to be an impressive display specimen. In thirty years, there have been only two exceptions to this situation: one was/is the rare but occasionally sizeable crystals from the Deccan Plateau trap rock quarries near Nasik. The other is the type offered here, from the driest desert on Earth: the Atacama of Chile. A typically massive variety, it comprised most of the matrix for the then newly-discovered mineral: Szenicsite, which appeared only once on the market. The Tierra Amarilla 'find' contained perhaps the least encountered form of Powellite: rare pseudomorphs of Powellite replacing crystals of Molybdenite. The replacement was so nearly complete that evidence for this supposition was equivocal. Most of what was excavated was massive, with frequent pockets of microcrystals, whereas, this spectacular specimen is one of the rare exceptions that seem to show a complete replacement of Molybdenite as platy crystals. The bright yellow fluorescing Powellite displays the foliations of the original Molybdenite better under shortwave UV rays than it does under daylight - which is why this specimen remained in the Hugh Ronemus collection for so long, it was his pick from the lion's share of this rare fluorescing mineral. The present specimen is more than two thirds Powellite, the remainder being mainly Quartz (itself somewhat scarce in this find). 3¼ x 2½ x 1¾-inches (8.3 x 6.4 x 4.4 cm). Offered at no reserve.
Provenance: Collected by Terry Szenics, ex. Hugh Ronemus Collection
Estimate: $300 - $500.
Condition report available upon request.
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