Arsenolite is a secondary mineral that forms as a white, often powdery alteration product of arsenic-bearing sulfides. Because it is highly soluble in water and very toxic, it is best kept in sealed containers and handled with extreme care by experienced collectors.
Is this arsenolite?
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 arsenolite with a known reference. Arsenolite sits at Mohs 1.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white to pale yellowish white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to silky.
- 4Match the color rangeCompare against the expected color range: white, blue, light yellow, red.
- 5Look at form & habitCrystal system: cubic. Typical habit: earthy, encrustations.
Often confused with
Arsenolite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside arsenolite
Minerals reported to co-occur with arsenolite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- As₂O₃
- Mohs hardness
- 1.5
- Density
- 3.87 g/cm³
- Colors
- Streak
- White to pale yellowish white
- Luster
- Vitreous to silky
- Transparency
- Transparent
- Crystal system
- Cubic
- Crystal habit
- Earthy, encrustations
- Cleavage
- {111}
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- An oxidation product of other arsenic-bearing sulfides in hydrothermal veins; may be formed in mine fires or in burning coal seams
Where rockhounds find arsenolite
Classic worldwide localities
- Manhattan, Nye Co., in the Ophir mine, Comstock Lode, Storey Co., at the Getchell mine, Humboldt Co., and from Simon, Mineral Co., Nevada, USA
- United Verde mine, Jerome, Yavapai Co., Arizona, USA
- Armagosa mine, San Bernardino Co., California, USA
- Wittichen, Black Forest, Germany
- Lauta, near Marienberg, Johanngeorgenstadt, and Annaberg, Saxony, Germany
- Jáchymov (Joachimsthal) and Kuttenberg, Czech Republic
Field-hunting tip
Where it forms: An oxidation product of other arsenic-bearing sulfides in hydrothermal veins; may be formed in mine fires or in burning coal seams. If you start seeing claudetite, realgar, orpiment in float, you are in the right ground. Typical habit: earthy, encrustations. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify arsenolite?+
Where is arsenolite found?+
Is arsenolite safe to handle?+
What rocks look like arsenolite?+
What minerals are found with arsenolite?+
What kind of rock does arsenolite form in?+
What is arsenolite used for?+
Find arsenolite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
