Abstract
Argentian tetrahedrites have been found, as crystals attaining 15mm across, in siderite-quartz-sulfide veins of the Taishu-Shigekuma mine, Tsushima Island. Electron probe microanalyses revealed that the chemical formula of the mineral is close to (Cu, Ag)10(Fe, Zn)2Sb4S13 with extremely wide range of silver content from 3.5 to 23.8 weight percent. The correlation between the unit cell edge (a0, Å) and the Ag content ([Ag] atomic %) of argentian tetrahedrites has been determined as a0=10.393+0.0128 [Ag].
