Senarmontite - Encyclopedia

    Class : Oxides and hydroxides
    Subclass : Oxides
    Crystal system : Cubic
    Chemistry : Sb2O3
    Rarity : Rare

Senarmontite is an uncommon antimony oxide resulting from alteration of the stibnite. It is found in the superficial oxidation zones of antimony deposits associated with other oxidized antimony minerals (cervantite, stibiconite, valentinite, etc...). It owes its name to Henri Hureau de Senarmont, professor of mineralogy at the Ecole des Mines in Paris, who was the first to study this mineral. Resinous to adamantine luster, colorless to gray depending on its degree of purity, it frequently occurs in translucent octahedral crystals, and in snowy white to white-gray masses. It is a mineral little known to collectors which can constitute an antimony ore.

Senarmontite in the World

The best samples, decimetric groups of centimetric crystals (up to 4 cm), come from its type-locality : Djebel Hamimat (Algeria), where this exceptionally abundant mineral was the main antimony ore ; magnificent centimetric octahedra colored in black by disseminated stibnite were also extracted there. Good crystals have been discovered in various antimony mines, especially in Canada (Red Lake, Lac Nicolet), in Italy (Celtine, near Siena), and in Slovakia (Pernek, Dubrava).

Senarmontite in France

In France, we find senarmontite in micro-crystals associated with stibnite in many deposits : Montlamard near Moulins (Allier), in various antimony mines in Haute-Loire such as La Bessade, at the La Forge mine near  Issoire (Puy-de-Dôme), at Rivet in Peyrebrune (Tarn), at the La Ramée mine (Vendée), etc...


Senarmontite has no twinned crystals known.

Fakes and scams

No scam known for this mineral.

Hardness : 2 to 2.5
Density : 5.5
Fracture : Irregular
Trace : White

TP : Transparent to translucent
RI : 2.087
Birefringence : None
Optical character : None
Pleochroism : None
Fluorescence : None

Solubility : Hydrochloric acid

Magnetism : None
Radioactivity : None