Senarmontite: Gemstones Information
Senarmontite is Sb2O3 and commonly forms transparent to translucent colourless or greyish white octahedra in the cubic system. The lustre is characteristically resinous or subadamantine. The hardness is 2–2.5 and the SG 5.3. The RI is 2.087. Facetable specimens are not common as crystals are brittle and appear colourless only by transmitted light.Senarmontite occurs by the oxidation of antimony, stibnite and other antimony minerals. Large crystals are reported from the Haminate mine,Sensa, Ain-el-Bebbouch, Qacentina, Algeria, though I have seen no specific reports of gem material being fashioned from the crystals.