Arsenolite - Encyclopedia

    Class : Oxides and hydroxides
    Subclass : Oxides
    Crystal System : Cubic
    Chemistry : As2O3
    Rarity : Fairly common

Arsenolite is an immediate oxidation product of native arsenic and arsenic sulfides in hydrothermal veins, and a sublimation product of burning collieries and burnt areas of mines. It was so named because of the arsenic it contains. It occurs in small colourless, bluish, yellowish or brownish millimetric octahedra, or in aggregates, masses and encrustations, botryoidal, stalactitic or earthy. It is a highly toxic mineral that contains arsenic in a soluble form.

Main photo : Arsenolite from the burning slag heaps of La Ricamarie, Loire, France © Chinellato Matteo

Arsenolite in the World

Arsenolite is a fairly common oxidation mineral in arsenic deposits around the world, but sites that have yielded quality specimens are rare. Arsenolite does, however, exist in fine, small crystals in the polymetallic arsenic mines of Saxony and Lower Saxony, Germany, and in the arsenic gold deposits of California and Nevada. A burnt shaft from the White Caps mine, near Manhattan (Nevada), which yielded some of the most beautiful crystals in the world.
Photo : Arsenolite from White Caps Mine, Nevada, USA © Antonio Borrelli

Arsenolite in France

In France, arsenolite is above all a mineral from burning mine dumps such as Decazeville (Aveyron) or Sorbiers (Loire), but also an oxidation product of arsenic discovered in the Vosges veins of Ste-Marie-aux-Mines.

Twinning and special crystallizations

No twin known for this mineral species.

Fakes and treatments

No fake or treatment identified for this mineral species. But the most beautiful crystals of arsenolite are however artificial and are "produced" by the processing plants where the arsenic ores are roasted.

Hardness : 1.5
Density : 3.87
Fracture : Conchoidal
Trace : White to pale yellow

TP : Transparent to translucent
RI : 1.755
Birefringence : 0
Optical character : None
Pleochroism : None
Fluorescence : None

Solubility : Warm water

Magnetism : None
Radioactivity : None