Thanks to Chris Tacker, Curator of Geology at the North Carolina Museum of Natural Sciences, for this guest post.
Museums and cultural institutions frequently get phone calls from prospective donors who want to give away Daddy’s or Granddaddy’s rock collection. Rock and mineral collections can support interesting and educational programs. However, these collections may hold a few surprises that open the institution to a number of unexpected regulatory and/or safety concerns. Radioactivity, radon, asbestos, toxins and carcinogens can all arrive as a part of amateurs’ collections.
To put this in perspective, any rock or mineral is a hazard if it’s moving fast enough. Any rock and mineral above a certain weight is a hazard to your head or feet. With reasonable care, hard hats, and steel toed shoes, these hazards can be minimized.
North Carolina has a remarkable mineral diversity, so there are some North Carolina specialties that turn up frequently in collections. Pegmatites in the Spruce Pine area are known for uranium-bearing minerals that are highly radioactive. Uraninite (pitchblende), torbernite, autinite, clarkeite, or samarskite are all NC minerals that have uranium as one of the principle structural elements. Apatite, monazite, zoisite (especially the pink variety known as thulite) and zircon can carry uranium or thorium as a minor or trace element. There are actually some collectors who specialize in radioactive minerals. Others prize torbernite and autinite because it fluoresces brightly in ultraviolet light.
If enough of these are gathered in one place, the radiation does represent a workplace hazard. These minerals will emit radon, which is a regulatory concern. More than one geologist or collector has possessed a stash of radioactive minerals, then discovered that they can’t sell their house, because the buyer’s radon tests show phenomenal levels of radon. More information on radon is available here.
Ultramafic rocks are composed of high magnesium, high iron, and low silicon minerals such as olivine and pyroxenes. Ultramafic bodies in the state can produce, and have produced, industrial sized portions of asbestos where the rocks have been metamorphosed. It’s easy to recognize because there are few furry minerals. (You can check out the fuzzy stuff at this site that sells asbestos minerals to collectors) But there are federal regulations on asbestos in all its forms. Problems with regulatory control are minor compared to the problems that museum staff will face if parents learn their child has handled asbestos, even if it is in a ziplock baggie.
You may not think of minerals as fire hazards, but several toxic minerals represent significant fire dangers. Cinnabar (mercury sulfide), orpiment (a very pretty orange or yellow arsenic sulfide, As2S3), and realgar (a very pretty red arsenic sulfide, AsS) emit very toxic gasses in a fire. Steam may make it worse. Firefighters are not prepared for arsenic and mercury gas. Worse, cinnabar and realgar are photosensitive, which means that they break down under visible light. They shed dust as they are displayed, a dust that is quite toxic. If these are in a collection, they need to be stored in a fireproof safe. There is no reason for any of these to be accessible to the public, much less to children.
These minerals double as ingestion/inhalation hazards. For example, realgar is a carcinogen, and is toxic because it contains arsenic. Aresenic accumulates in the human body, as does the mercury from cinnabar. Pretty silver cubes of galena are made of lead sulfide. Lead accumulates in the body, so I recommend that children don’t handle it. A good handwashing will take care of most of the ingestion hazards, but handwashing combined with staying far away from it works even better.
If these are hazardous, why do we keep them in our collection? The Geology Collection at the Museum of Natural Sciences supports education and exhibits, but we are primarily a research collection. We have loaned out asbestos samples from defunct mines to support asbestos research and litigation. Radioactive minerals are extremely valuable for research into isolation of radioactive wastes. What happens to the atomic structure of a mineral or a glass when exposed to long-term radioactivity? Nature has already conducted the experiment. Where else are you going to find a material that has been subjected to radiation for thousands or millions of years?
So be suitably careful and remember: Any mineral moving at high velocity is hazardous.