Uraninite with Clarkeite "Gummite)

specimen number:
2063511

location:
Ruggles Mine, Grafton, New Hampshire, USA

description:
Classic for this locality, a specimen rich throughout with masses of black uraninite and brown clarkeite. There are other secondary uranium oxides present as well, these specimens are often referred to by the varietal name gummite. The specimen has been sawn on one face to show the interior. The specimen comes with a previous label from the collection of Ray DeMark.

Located in Grafton, Grafton County, New Hampshire, the Ruggles Mine is a historic open-pit pegmatite deposit famous for its extraordinary yield of industrial mica, feldspar, beryl, and uranium minerals. Discovered around 1803 by Sam Ruggles, it stands as the oldest commercial mica mine in the United States, operating for nearly two centuries before closing active production and operating as a popular tourist collecting site until the late 2010s. The site cuts into a Devonian complex known for coarse-grained granite pegmatites that experienced secondary alterations, concentrating heavy radioactive minerals alongside rich suites of lithium, beryllium, and phosphorus. Among these secondary species is gummite, a historical rock-term referring to a gum-like, orange-yellow to reddish-brown mixture of secondary uranium minerals formed through the intense oxidation and hydration of primary uraninite. Over its long history, the locality yielded exceptional museum-quality specimens and served as a renowned destination for amateur mineral collectors and mineralogists alike.

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