This is a really good piece of Stibarsen, a rare arsenic antimonide alloy, from this famous mineral producing region in the Czech Republic. For years, stibarsen was labeled as allemontite, which is no longer a species. The species is now stibarsen, and allemontite is an archaic/invalid term. This piece features the classic botryoidal form that is well-known from Pribram. A good representation of this classic old material. From the collection of Juan M. Casanova.