top of page
Chris Clemens

Hyalite Opal, Chalk Mountain Mine, Spruce Pine, North Carolina

Hyalite opal from the Chalk Mountain Mine, in Spruce Pine, North Carolina, provides a classic example of uranyl-activated green fluorescence, and is one of the most brightly fluorescent minerals. This specimen consists of glassy hyalite opal (Opal-AN) on a light-colored granite pegmatite matrix. The opal shows brilliant green fluorescence under short wave UV, and a bright green response under long wave also. The size of this specimen is 10.2 x 8.9 x 6.3 cm, and the area of fluorescent opal is approximately 6.4 x 4.4 cm.


Interestingly, because the hyalite contains trace amounts of the element uranium, it is slightly radioactive.

As shown above, the hyalite opal fluoresces a brilliant green under short wave UV (254 nm).

Under long wave UV (365 nm), the hyalite shows a bright green/yellow response.

Same specimen shown under visible light. Note the crust of hyalite opal on the surface of the granite pegmatite host rock.

437 views

Recent Posts

See All
bottom of page