Which minerals are toxic, radioactive or otherwise hazardous?
Updated
On this page8
Only a small share of mineral species can hurt you, and the National Park Service names them in two curator's notes: Conserve O Gram 11/11 for toxic elements, mercury vapor, acid-forming sulfides and asbestos, and 11/10 for radioactive minerals [1][2]. The hazards fall into five kinds: toxic elements, asbestiform fibers, radioactivity, mercury vapor and acid released as a mineral breaks down. This page lists the species a collector or crystal seller is most likely to own in each group, what the hazard is, and the precaution the NPS gives. It also explains why a polished stone on a shelf and the same stone on a saw are different problems.
The five ways a mineral can hurt you
The NPS note opens with a point worth keeping in mind before reading any list: of the roughly 3,600 species recognized when it was written in 2006, "only a small subset" pose a potential health hazard [1]. (The species count has grown since; the current figure and its date live on species, variety and trade names.) The hazard depends on what the mineral is made of and on what you do to it.
| Hazard | How it reaches you | What the NPS says to do | Where it is covered in depth |
|---|---|---|---|
| Toxic elements | Dust inhaled or swallowed; residue on hands | Neoprene gloves, wash hands after handling, respirator when cutting or trimming [1] | Handling and storing toxic minerals |
| Asbestiform fibers | Fibers released into the air and inhaled | Store in a sealable, clearly marked bag so particles cannot become airborne [1] | Asbestiform minerals |
| Radioactivity | External radiation at close range; radon gas and its decay products in closed spaces | Latex or nitrile gloves, wash hands, distance, ventilation to outside, signage [2] | Radioactive minerals at home |
| Mercury vapor | Vapor given off by the mineral, and by liquid mercury inside some specimens | Treat as a toxic-element mineral; the NPS warns body temperature can vaporize the mercury and the vapor is absorbed through the skin [1] | Handling and storing toxic minerals |
| Acid released by decay | Sulfur dioxide from decaying pyrite, which forms sulfuric acid with water | Keep humidity below the level that starts decay [1] | Pyrite decay |
A sixth hazard belongs to the work rather than to any species: fine quartz dust from sawing, grinding and tumbling. It has its own page, silica dust from cutting, grinding and tumbling, because it affects anyone who cuts almost any rock.
The toxic elements, as the NPS lists them
Conserve O Gram 11/11 names twelve elements of concern in geological collections: aluminum, antimony, arsenic, beryllium, bismuth, bromine, cadmium, lead, mercury, selenium, thallium and uranium [1]. It adds that toxic metals are "persistent and cumulative" in their effects, which is the reason small, repeated exposures at a bench matter more than one careless afternoon [1].
A mineral is a concern when one of those elements is an essential part of its composition. The table below takes common collector species and gives the element that puts each on the list and the form the hazard takes. Formulas are given only where the NPS note or the International Mineralogical Association list states them [1][3]; check any species you are unsure of against its IMA entry. It is a working list for a home collection, not a complete one. If a species you own contains one of the twelve elements, treat it the way this page and the handling page describe, whether or not it appears here.
| Species | Element of concern | Notes for a collector |
|---|---|---|
| Realgar | Arsenic | An arsenic sulfide; soft and crumbles to orange powder |
| Orpiment | Arsenic | An arsenic sulfide; soft and flaky, sheds powder when handled |
| Arsenopyrite | Arsenic | FeAsS on the IMA list [3]; hard and stable in the hand, a dust hazard when crushed or cut |
| Galena | Lead | PbS, named in COG 11/11 [1]; heavy, cleaves into cubes, leaves gray residue on fingers |
| Cerussite, vanadinite, wulfenite, crocoite | Lead | Lead minerals common in the specimen and decor trade; crocoite forms fragile needles that shed fragments |
| Cinnabar | Mercury | HgS, named in COG 11/11 as a source of mercury vapor; may hold beads of liquid mercury [1] |
| Stibnite | Antimony | An antimony sulfide; soft, bends and breaks into splinters |
| Greenockite | Cadmium | A cadmium sulfide, usually a thin yellow coating on other minerals |
| Beryl (emerald, aquamarine) | Beryllium | Stable as a crystal in the hand; the concern is dust from cutting |
| Uraninite, autunite, carnotite | Uranium | Radioactive as well as chemically toxic; autunite is Ca(UO₂)₂(PO₄)₂(H₂O)₁₁ on the IMA list [3]; see the radioactive page [2] |
Five of the lead minerals above (cerussite, crocoite, galena, vanadinite and wulfenite) are also on the list of eleven lead-based minerals that the Consumer Product Safety Commission excludes from its finding that natural minerals do not exceed children's product lead limits [4]. If you assemble kits or sell to children, the full list and what it means are on children's product rules for rock kits.
Asbestiform, radioactive and acid-forming species
Asbestiform minerals. COG 11/11 names six: chrysotile, crocidolite (described there as a variety of riebeckite), amosite, anthophyllite, tremolite and actinolite [1]. The diseases it lists are lung cancer, mesothelioma and asbestosis [1]. Tremolite and actinolite also occur in non-fibrous crystals, which is why the word that matters on a label is "asbestiform," meaning the fibrous habit. The asbestiform minerals page covers recognizing and storing them.
Radioactive minerals. COG 11/10 gives autunite, brannerite, carnotite, monazite, thorianite and uraninite as common examples, and notes that most of the radioactivity comes from uranium-238 or thorium-232 [2]. It also warns that uranium minerals can be deposited in fossil bone and wood, so a radioactive specimen is not always one labeled as a uranium mineral [2].
Sulfides that release acid. COG 11/11 names chalcopyrite, galena and pyrite among the sulfides, and native sulfur alongside them [1]. In humidity above 60 percent, it says, pyrite can release sulfur dioxide, which combines with water to form sulfuric acid [1]. That acid attacks the specimen, its label and anything stored with it. The humidity bounds and their source are on humidity, high and low.
Decor stones that belong on the list
Crystal shops and market tables carry several of these species as polished pieces, spheres and tumbled stones, often without a word about what they contain.
- Galena is sold as cubes and clusters. It is lead sulfide, named by the NPS as a toxic-element sulfide [1], and it leaves a gray streak on skin and paper.
- Cinnabar is sold as rough and as polished pieces in matrix. The NPS singles it out because mercury vapor is "readily liberated" from it [1].
- Vanadinite and wulfenite are popular for their color and are lead minerals; both are on the CPSC's list of lead minerals excluded from its natural-materials finding [4].
- Malachite is a copper carbonate. Copper is not one of the twelve elements on the NPS list [1]. Malachite is on many caution lists for a different reason: it is soft, it is cut and carved in quantity, and the NPS's general warning about dust applies with full force to anyone who saws, grinds or sands it [1]. A polished malachite sphere on a shelf is a different object from a malachite slab on a wet saw.
None of this means a shop should not sell these stones. It means the seller should know what each one is, label it, keep it out of children's products where the CPSC exclusion applies, and tell buyers not to grind, cut or put it in water they will drink. The page on starting a crystal and decor business covers how these stones fit a retail mix.
Why a polished piece on a shelf differs from the same stone on a saw
The most useful single sentence in COG 11/11 is this one: "Inhaling mineral dust may be more of a hazard than handling the specimen" [1]. The note explains that how much dust a specimen gives off depends on how friable it is (how easily it crumbles) and on how it is handled [1].
That gives a practical scale of risk for any toxic-element species:
| What you are doing | Exposure | The NPS precaution that applies |
|---|---|---|
| Looking at a hard, stable crystal in a closed box | Very low | Label the box and the cabinet [1] |
| Handling a hard, polished piece | Low; residue on skin | Gloves for toxic-element minerals, wash hands afterward [1] |
| Handling a soft or friable specimen (realgar, orpiment, crumbling galena, fibrous material) | Higher; loose powder and fragments | Gloves, wash hands, keep it boxed so fragments stay contained [1] |
| Trimming, cutting, sanding or grinding | Highest; airborne dust | A good-quality respirator, "especially if they are being cut or trimmed" [1] |
The same logic covers mercury in a different way. A cinnabar specimen with visible droplets of mercury is a vapor source at room temperature, and the NPS adds that body heat vaporizes the metal, so it should not be held in a bare hand [1].
What to do if you think you have been exposed
The NPS notes describe precautions, not treatment. If someone, particularly a child, has swallowed a fragment or powder from a toxic-element or radioactive mineral, call your local poison control center right away and keep the specimen or its label to tell them what it is. For symptoms after working with dust, see a doctor and tell them which minerals you were cutting. For mercury spilled from a specimen, follow the agency cleanup steps on getting rid of hazardous specimens rather than vacuuming it.
From the list to the cabinet
Knowing which species are hazardous is the first step. The next is how to handle, label and store them so that the hazard stays inside the box: gloves, washing, sealed and labeled storage, warning symbols on the cabinet and keeping the drawer away from children and pets. That routine is on handling and storing toxic minerals.
References
- National Park Service, Conserve O Gram 11/11, *Health and Safety Issues with Geological Specimens*, Greg McDonald, September 2006. https://www.nps.gov/subjects/museums/upload/11-11_508.pdf
- National Park Service, Conserve O Gram 11/10, *Radioactive Minerals*, Greg McDonald, September 2006. https://nps.gov/subjects/museums/upload/11-10_508.pdf
- International Mineralogical Association, Commission on New Minerals, Nomenclature and Classification, *The New IMA List of Minerals: A Work in Progress*, updated July 2026. https://cnmnc.units.it/files/editor/IMA_Master_List_%282026-07%29.pdf
- U.S. Consumer Product Safety Commission, *Children's Products Containing Lead; Determinations Regarding Lead Content Limits on Certain Materials or Products*, 74 FR, August 26, 2009 (16 CFR 1500.91). https://www.govinfo.gov/content/pkg/FR-2009-08-26/pdf/E9-20589.pdf
