The Mineral STIBARSEN

Chemistry: SbAs, Antimony Arsenic
Class: Native Elements
Subclass: Non-metals
Uses: A very minor ore of antimony and arsenic and as mineral specimens.
Specimens

Stibarsen is named for its chemistry and is an unusual Elements Class mineral. The "stib" in the name is for the Latin word for antimony, stibium; from where antimony gets its symbol, Sb. The closely related elements antimony and arsenic are semi-metals meaning they share some properties with metals such as metallic luster and at least some electrical conductivity; but differ in other characteristics such as a tendency to bond with covalent bonds instead of with metallic bonds. Stibarsen, which has also been known as allemontite, is classified as an element despite the fact, that in chemical reality, it is a compound! The reason for this is that the elemental bonds that exist between antimony and arsenic are very similar to the bonds of other non-metallic elemental minerals such as diamond or sulfur. If the arsenic or antimony were bonded to a true metal instead of a semi-metal then the mineral would be classified in the Sulfides Class instead of the Native Elements Class.

Stibarsen is a very rare mineral, but is a joy to see. It has a bright silvery color and a good botryoidal habit. The effect presents to the viewer a mass of what appears to be a highly polished rounded mass of high grade silver!

PHYSICAL CHARACTERISTICS:

Color is silver, white, reddish-white to gray.
Luster is bright metallic.
Transparency: Specimens are opaque.
Crystal System is trigonal.
Crystal Habits is limited to botryoidal masses.
Cleavage is perfect.
Fracture is hackly.
Hardness is 3 - 4
Specific Gravity is 6.0 - 6.3 (above average for a metallic mineral)
Streak is gray black.
Associated Minerals include apatite, beryl, microcline, micas and other pegmatite minerals.
Notable Occurrences are limited to the type locality at the quarry at Varutrask, Vasterbotten, Sweden and also at Trebsco, Bohemia; Rio Moctezuma, Sonora, Mexico.
Best Field Indicator is crystal habit, color, luster, locality and density.