Native arsenic is a brittle, metallic mineral that typically occurs in reniform or botryoidal masses with a characteristic tin-white color that quickly tarnishes to a dull grey or black. It is primarily found in hydrothermal vein deposits alongside other arsenic sulfides and silver minerals. Due to its high toxicity, collectors should handle samples with caution and store them in sealed containers.
Is this arsenic?
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 arsenic with a known reference. Arsenic sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: tin-white.
- 3Read the lusterHold the specimen under a strong light. Luster: nearly metallic.
- 4Match the color rangeCompare against the expected color range: lead gray, gray, white.
- 5Look at form & habitCrystal system: trigonal. Typical habit: lamellar, nodular, reniform.
Often confused with
Arsenic vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Arsenic leaves tin-white, Antimony leaves gray; luster reads nearly metallic on Arsenic and metallic on Antimony.
How to tell apart: Arsenic is noticeably harder (Mohs 3.5 vs. 2-2.5); streak differs, so Arsenic leaves tin-white, Bismuth leaves pale silver; luster reads nearly metallic on Arsenic and metallic on Bismuth.
How to tell apart: Arsenopyrite is the harder of the two (Mohs 5.5-6 vs. 3.5); streak differs, so Arsenic leaves tin-white, Arsenopyrite leaves black; luster reads nearly metallic on Arsenic and metallic on Arsenopyrite.
Often found alongside arsenic
Minerals reported to co-occur with arsenic. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- As
- Mohs hardness
- 3.5
- Density
- 5.63-5.78 g/cm³
- Streak
- Tin-white
- Luster
- Nearly metallic
- Transparency
- Opaque
- Crystal system
- Trigonal
- Crystal habit
- Lamellar, nodular, reniform
- Cleavage
- Perfect on {0001}, fair on {1014}
- Rarity
- Uncommon
- Uses
- Collector, Specimen
- Host rock
- In hydrothermal veins and deposits that contain other arsenic minerals; may be in Co–Ag sulfide veins
Where rockhounds find arsenic
6 mapped spotsClassic worldwide localities
- Sterling Hill, Ogdensburg, Sussex Co., New Jersey and Washington Camp, Santa Cruz Co., Arizona, USA
- Freiberg, Schneeberg, Johanngeorgenstadt, Marienberg, and Annaberg, Saxony, Germany
- Wolfsberg and St. Andreasberg, Harz Mountains, Germany
- Wieden, Black Forest, Germany
- Gabe-Gottes mine, Rauenthal, near Sainte-Marie-aux-Mines, Haut-Rhin, France
- Jáchymov (Joachimsthal), Příbram, and Cínovec (Zinnwald), Czech Republic
Field-hunting tip
Where it forms: In hydrothermal veins and deposits that contain other arsenic minerals; may be in Co–Ag sulfide veins. If you start seeing arsenolite, cinnabar, realgar in float, you are in the right ground. Typical habit: lamellar, nodular, reniform. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Nevada, Alabama, Montana. Start trip planning there.
More arsenic photos
Common questions
How do you identify arsenic?+
Where is arsenic found?+
Can I find arsenic in the United States?+
Is arsenic safe to handle?+
What rocks look like arsenic?+
What minerals are found with arsenic?+
What kind of rock does arsenic form in?+
What is arsenic used for?+
Find arsenic on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
