About
Any mixture of arsenic and antimony that constitutes 80% or more of one element is classified as that element. For example, a specimen with a ratio of 80% arsenic and 20% antimony is recognized as Arsenic. Conversely, a specimen with 80% antimony and 20% arsenic is recognized as Antimony. Any combination with less than 80% of either arsenic or antimony is classified as Stibarsen.
Crystal Forms & Aggregates
Other ID Marks
Striking Features
Environment
Varieties
✓ common · ✗ uncommon
- Allemontite— Any mixture of arsenic and antimony, including Stibarsen.
(Allemontite is not scientifically recognized as a mineral species, but rather a descriptive name.) - Allemontite I— Allemontite with a greater content of antimony than arsenic.
- Allemontite II— Allemontite that has an equal quantity of antimony and arsenic.
- Allemontite III— Allemontite with a greater content of arsenic than antimony.
Noteworthy Localities
U.S. occurrences of Stibarsen are the Ophir Mine, in the Comstock Lode, Storey Co., Nevada; and at American Eagle, Gunnison Co., Colorado.

