Relationship of chemical composition to reflectivity and Vickers hardness of fahlore

Abstract

The relationship of chemical composition to reflectivity and Vickers hardness of fahlore was examined by electron microprobe analyzer, microscope photometer and microhardness tester. 95 specimens of fahlore from ores of Tertiary epithermal gold- and silver-bearing quartz vein, polymetallic sulfide vein and Kuroko, and Silurian stratabound massive sulfide deposits were used for this study.
The maximum amounts of respective constituents of fahlore are 35.9 atom.% Cu, 18.5 atom. % Ag, 8.2 atom. % Zn, 6.4 atom.% Fe, 14.9 atom.% Sb and 13.6 atom.% As. The ranges of reflectivity of fahlore are 26.9-31.5% at 450 nm, 27.7-31.6% at 530 nm and 26.4-31.0% at 600 nm. And the range of Vickers hardness is 276-389.
There are close relationships among Sb/(Sb+As) ratio, reflectivity at 600 nm in air and lattice constant, and between Agcontent and Vickers hardness of fahlore.
The relationship between reflectivity and Vickers hardness of fahlore is useful for identification of tetrahedrite, Ag-tetrahedrite and tennantite.