Lush patch of Autunite on feldspar matrix fluoresces bright green under short-wave UV light. This beautiful specimen is radioactive due to its uranium content and measures Size: 2-1/8"x3-1/4". It was discovered in the Chalk Mountain Mine, of Chalk Mountain in Spruce Pine, Mitchell County, North Carolina. This is a fabulous radioactive specimine.
Autunite is one of the more attractive and popular radioactive minerals. To state the obvious, the uranium in its chemical formula provides this radioactivity. Autunite is probably the most popular uranium mineral for collectors. Its green and yellow color shades seem to glow and are actually fluorescent. The crystal aggregates look like inflated mica books and are very distinctive. The structure is composed of phosphate tetrahedrons linked to uranium-oxygen groups that form distorted octahedrons. The phosphates and uranium groups lie in sheets that are weakly held together by water molecules. This structure produces the tabular habit, the one perfect direction of cleavage, and the relative softness.
Autunite can lose water and convert to a different mineral called meta-autunite-I of the meta-autunite/meta-torbernite group of minerals and with heating can produce a meta-autunite-II mineral. Oddly, neither mineral is found in nature in any appreciable abundance. However, the conversion is irreversible and ongoing, and all collection specimens of a certain age are at least partially converted. Eventually after many years the meta-autunite will powder, and the specimen will be ruined. Fine autunite specimens should be stored in a closed container to avoid water loss. Some drastic measures have been attempted on fine museum quality specimens to thwart the conversion to meta-autunite, including lacquering. Remember, this is also a radioactive mineral and should be stored away from other minerals that are affected by radioactivity, and human exposure should be limited.
This specimen is in compliance with USPS regulations specified in Pub. 52, Exhibit 347.22, and 49 CFR 173.42
