The random letter was "T" so Torbernite.

Torbernite, whose name derives from the Swedish chemist Torbern Bergman (1735-1784), is a radioactive, hydrated green copper uranyl phosphate mineral, found in granites and other uranium-bearing deposits as a secondary mineral. Torbernite is isostructural with the related uranium mineral, autunite.

The chemical formula of torbernite is similar to that of autunite in which a Cu2+ cation replaces a Ca2+. The number of water hydration molecules can vary between 12 and 8, giving rise to the variety of metatorbernite when torbernite spontaneously dehydrates. Their respective chemical compositions are the following:

Torbernite

Cu(UO2)2(PO4)2·12 H2O
Metatorbernite

Cu(UO2)2(PO4)2·8 H2O
Torbernite's most common alternative names are copper uranite and cupro-uranite.


Uses of torbernite

As a radioactive mineral, torbernite has some limited significance as a uranium ore. Its rich green color and well-developed distinctive crystals (size: mm to a few cm) make it a sought-after collector's mineral, as well. However, torbernite, like other hydrated minerals, can easily suffer from loss of water molecules. This loss of water from the mineral leads to an alteration of torbernite specimens into its pseudomorph, meta-torbernite. Some collector's websites assert that any torbernite specimen more than a few years old should be considered fully transitioned to meta-torbernite. However, it likely depends on the temperature and relative humidity of ambient air in which specimens are stored.

As torbernite is radioactive and outgases radon (222Rn), collectors are urged to take proper precautions in the handling and storage of any specimens. An adequate ventilation of the rooms and the cabinets in which the specimens are stored is essential to evacuate the radioactive radon gas responsible for lung cancer, but it could increase the dehydration rate of the specimens. To limit radon inhalation, naked specimens should never be stored in rooms in which one spends much living or working time. An alternative is to store specimens in gas tight transparent containers in which radon will accumulate and decay to secular equilibrium.

Associated minerals

Torbernite frequently occurs in conjunction with other uranium minerals, as well as host rock minerals. These associated minerals include:

autunite, Ca(UO2)2(PO4)2 · 8 - 12 H2O
uraninite, UO2
uranophane, Ca(UO2)2Si2O7 · 6 H2O
uranocircite, Ba(UO2)2(PO4)2 · 8 - 12 H2O
topaz, Al[(F,OH)2|SiO4]

Identification

The most obvious factor in identifying torbernite is its radioactivity. However, since it is frequently found in association with other radioactive minerals, this may not be useful in separating one uranium mineral from the rest. A next step would be to check color. Most uranium-bearing minerals are bright yellow or green. As torbernite is exclusively green, this can be a useful secondary fact. Crystal habit is also useful, but as it shares a similar structure and color with autunite. Nonetheless, regardless of identification, it is likely that at least some of the specimen will have already altered to meta-torbernite.

And the Widipedia link for this information:  https://en.wikipedia.org/wiki/Torbernite

Yes, that's a different Torbenite than what we have around here.
Very nice. Thanks for the pic.

Anything green, my favorite color, is okay by me.  Great specimens Laurie and Dennis, thanks for posting them.  I think I may have to invest in purchasing a fine specimen very soon.

rockytoprockshop wrote on Sep 8^th, 2015 at 2:01pm:



No, but hopefully Laurie or Dennis know something about that.  It would be great to be able to collect some from NC.

Dennis,

You got point there, smoky mainly gets its color from trace elements of radioactivity in the host rock and true Wake County certainly has the smoky quartz. I was just curious if anyone had ever seen a torbernite from anywhere outside of Spruce Pines area? There were other radioactive minerals in some of the other mountain pegmatite regions such as in Graham and Swain counties. There are reports of uraninite, columbite, monazite, etc. in the Kings Mountain belt through Cleveland, Gaston, and Lincoln Counties and of course again the Davie County occurrence but that seems to be the most eastern localities for U minerals. I imagine that in some of the granite quarries in Rowan, Mecklenburg, on over towards Wake that there are small amounts of radioactive minerals that so micro that they haven't been identified yet. It would be interesting to take a Geiger counter into some of these eastern granite quarries to see what you'd find. Like I was saying earlier, the Vulcan pit here near my house contains very thin almost invisible fluorescent coatings that will fluoresce pale yellow green and the calcite seems are even brighter. The last time I was in there I noted some black massive material on a few samples that were unimpressive but I wish that I'd kept one to test as it might have been a U mineral. Whatever the case, Spruce Pines area is unarguably the best and most prolific source of U minerals in the state but I find some of the other less likely localities interesting too. The flat garnets from Wake County in mica remind me so much of Spruce Pines that one has to ponder the possibility that Wake County has pegmatites that contain other "Spruce Pine type" minerals also, maybe U minerals! Anyway, Dennis give me a call sometimes its been a while. Hope your doing good.

Take care,

Mike