Formula: As4S4
Sulphide of arsenic, paramorph of pararealgar and realgar (all three minerals are monoclinic), forms a continuous series with alacránite
Crystal System: Monoclinic
Specific gravity: 3.542 calculated
Hardness: 2½
Streak: Dark orange
Colour: Orange

Hydrothermal environments
Coal-seam fires

Bonazziite is a relatively new mineral, approved in 2013. It is associated with low temperature epithermal mercury - antimony - bismuth deposits and vapour deposited environments, both burning coal and volcanic. Common associates include arsenolamprite, orpiment and realgar.
As realgar (but unlike alacránite), bonazziite alters to pararealgar in polychromatic and monochromatic light (Mindat).


There are two co-type localities, the Alacrán mine, Alacrán, Pampa Larga mining district, Tierra Amarilla, Copiapó province, Atacama, Chile, and the Khaidarkan Sb-Hg deposit, Batken Region, Kyrgyzstan.

From the Khaidarkan Sb-Hg deposit, Batken Region, Kyrgyzstan, the sample containing bonazziite was not found in situ, but it is a museum sample, was labelled "wakabayashilite Khaidarkan, Osh Oblast, Kyrgyzstan".
The Khaidarkan Sb-Hg deposit is the type locality for seven other minerals: chursinite, galkhaite, khaidarkanite, kuznetsovite, poyarkovite, shakhovite and velikite. In the rock sample, about 4 x 5 x 9 cm3 in size, bonazziite occurs rarely in the intermediate region between sulphur and realgar in a calcite matrix. The bonazziite occurs as subhedral to anhedral grains and shows no inclusions of, or intergrowths with, other minerals. The maximum grain size of bonazziite is about 100 microns. Other spatially associated minerals are wakabayashilite, alacránite and stibnite (MM 79.1.121–131).
Bonazziite is a low-temperature hydrothermal mineral probably formed while the system had direct involvement of magmatic volatiles (HOM).

At the Ermakovite and Novikovite type locality, Ravat Kishlak, Ayni District, Sughd, Tajikistan, ermakovite is a fumarolic mineral formed directly from gas from a natural underground coal fire. Associated minerals include sulphur, realgar, salammoniac, alacránite, bonazziite and thermessaite-(NH4) (MM 87.1.69–78).

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