Abstract
Antimony ores from El Antimonio, Sonora, Mexico, contain a new mineral corresponding in chemical composition and structure with magnesium antimonate, MgSb2O6, although in the mineral the lattice is deficient in magnesium and some of the oxygen is replaced by hydroxyl groups. The mineral is massive, color blue-gray, streak light gray, hardness about 7, density 5.7. The mean index of refraction varies from 1.86 to 1.91, the birefringence is approximately 0.01. The mineral occurs in quartz veins associated with stibiconite. x-ray investigation shows that it is tetragonal (ditetragonal dipyramidal), a = 4.68 Å, c = 9.21 Å, c/a=1.968, space group P4/mnm; the structure is of the trirutile type, and the mineral is isomorphous with tapiolite and with many artificial antimonates and tantalates. The'name bystromite is proposed after Anders Byström, Swedish crystal chemist, who worked out the structure of synthetic magnesium antimonate in 1941.
