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SC396 - Powellite after Molybdenite

Locality: Holts Ledge, Lyme, Grafton Co., New Hampshire, USA (MINDAT)
Size: 6 x 4 x 2 cm - Miniature (3-6 cm)
Weight: 31.9 g
minID: 1LL-C6R

Powellite pseudomorph after molybdenite. Hexagonal, platy molybdenite crystals degrading into powellite, in most cases leaving just a cast, like for the crystal on the top right. In some cases, the substitution is only partial, like for the crystal on the top left, where some black, metallic molybdenite is still visible. The powellite has a strong yellow fluorescence under shortwave UV light. The hexagons are about 5 mm in size.

Photo in normal light.
Fluorescence under shortwave UV light (254nm Hg light).
Fluorescence spectrum under 275nm UVC LED excitation.
Last update: 24 June 2021