Uraninite

Specimen Origin: Ruggles Mine (Grafton, New Hampshire, USA)

The Ruggles Mine, situated atop Isinglass Mountain in Grafton, New Hampshire, is a historic open-pit pegmatite worked for over 150 years, primarily producing mica, feldspar, and beryl. Within its coarse-grained granite pegmatite bodies, uraninite occurs in small quantities, often found as dendritic masses in fractures or in association with alteration products such as gummite and accessory minerals like zircon. These occurrences illustrate the complex secondary processes in pegmatite uranium minerals and are of interest to both collectors and mineralogists.

Uraninite

Uraninite, historically also called pitchblende, is a uranium oxide mineral with a composition close to UO₂, often variably oxidized toward U₃O₈ and containing lead, thorium, and rare-earth elements. It typically appears as black, massive to granular material, sometimes showing octahedral crystal forms, with a submetallic to greasy luster. With a Mohs hardness of 5–6 and very high density, it is strongly radioactive and is the primary ore mineral of uranium.