Native selenium is a rare elemental mineral often found as needle-like crystals or powdery encrustations in hydrothermal deposits. It is known for its distinct metallic grey to reddish-grey appearance and is chemically sensitive, requiring careful storage to prevent degradation.
Is this selenium?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch selenium with a known reference. Selenium sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: red.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: gray, purple gray, reddish.
- 5Look at form & habitCrystal system: trigonal. Typical habit: crystalline, disseminated, granular.
Often confused with
Selenium vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside selenium
Minerals reported to co-occur with selenium. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Se
- Mohs hardness
- 2
- Density
- 4.80 g/cm³
- Streak
- Red
- Luster
- Metallic
- Transparency
- Opaque, transparent in very thin fragments
- Crystal system
- Trigonal
- Crystal habit
- Crystalline, disseminated, granular
- Cleavage
- Good on {0112}
- Rarity
- Rare
- Uses
- Collector, Industrial
- Host rock
- Formed at relatively low temperatures by sublimation of fumarolic vapors, and from oxidation of selenium-bearing organic compounds in sandstone U–V deposits; from burning coal and pyritic ores
Where rockhounds find selenium
2 mapped spotsClassic worldwide localities
- United Verde mine, Jerome, Yavapai Co., Arizona, USA
- Colorado Plateau, as in the Peanut mine, Bull Canyon, Uravan district, Montrose Co., Colorado, and the Parco No. 23 mine, Thompsons district, Grand Co., Utah, USA
- Road Hog No. 1A mine, Black Hills, Fall River Co., South Dakota, USA
- Mopung Hills, Churchill Co., and the Gold Quarry mine, near Carlin, Eureka Co., Nevada, USA
- Moctezuma (Bambolla) mine, 12 km south of Moctezuma, Sonora, Mexico
- Pacajake mine, Hiaco, 24 km east-northeast of Colquechaca, Potosí, Bolivia
Field-hunting tip
Where it forms: Formed at relatively low temperatures by sublimation of fumarolic vapors, and from oxidation of selenium-bearing organic compounds in sandstone U–V deposits; from burning coal and pyritic ores. If you start seeing pyrite, ferroselite, zippeite in float, you are in the right ground. Typical habit: crystalline, disseminated, granular. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Utah. Start trip planning there.
Common questions
How do you identify selenium?+
Where is selenium found?+
Can I find selenium in the United States?+
Is selenium safe to handle?+
What rocks look like selenium?+
What minerals are found with selenium?+
What kind of rock does selenium form in?+
What is selenium used for?+
Find selenium on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
