FREIESLEBENITE, a rare mineral consisting of sulphanti monite of silver and lead The monoclinic crystals are prismatic in habit, with deeply striated prism and dome faces. The colour is steel-grey, and the lustre metallic ; hardness 21, specific gravity 6.2. It occurs with argentite, chaly bite and galena in the silver veins at Freiberg, Saxony, where it has been known since 172o. The species was named after J. K. Freiesleben, who had earlier called it Schil f -Glaserz. Groups of large crystals have come from Hiendelaencina near Guadalajara in Spain.