Summary: Optical and other microproperties of owyheeite Pb₅Ag₂Sb₆S₁₅ are presented and details given of a new locality for this rare sulpho-salt. Apparent rotation of the plane of polarization (3·5°), microhardness (112 V.H.N.), and polarization effects are all very similar to those of the other feather ores, jamesonite and boulangerite. An intimate association with pyrargyrite is further noted.