What is Hyalite Opal And Is It Radioactive?

A few months ago, I came across a photo of this glow in the dark opal. Some of the research I was reading up on said that it glowed due to low levels of uranium in the opal, which is a pretty rare opal. It sounded unreal and I mentally put the gem on my bucket list of stones I would love to have and work with.

And at the Mother’s Day Gem and Mineral show in Marietta, GA this weekend, I was able to scratch that gem off of my bucket list. 



According to this website, they’ve tested a few radioactive minerals including Hyalite—they got theirs from the same mine my piece came from (Chalk Mountain Mine, Spruce Pine, NC) and the results showed that their Hyalite emitted a radioactivity level of 300 cpm.

CPM means counts per minute and measures radioactivity. It’s the number of atoms in a given quality of radioactive material that are detected to have decayed in one minute.

Another Hyalite they obtained from Mexico emitted 500 cpm.


How Safe Is Hyalite?

HPS Specialists in Radiation Protections runs a Q&A section on their website and someone asked if wearing a Hyalite ring was safe. The question was answered by Ray Johnson who has a Masters of Science among other degrees that he has listed with his signature.

Ray explains that due to the type of uranium in this opal it is pretty safe. In fact, he mentions that uranium has and is still being used in coloring glassware. The U.S. Nuclear Regulatory Commission (NRC) allows the use of uranium in glassware up to 10% by weight, although only a fraction of 1% is commonly used.

Ray also explains that due to uranium being a beta-particle emitter, the radiation from a trace amount in hyalite is self-shielded within the crystal. He also says that the beta energy from uranium has nothing to do with the fluorescence–meaning the brighter hyalite glows has nothing to do with how radioactive the mineral is (my interpretation anyway).

You can read more info from Ray’s answer, here.