The world's largest known crystal of stolzite (1.3 X 1.3 X 2.5 cm) is described. It is associated with tennantite and quartz, and is from the Tsumeb mine, Tsumeb, Namibia. Forms present include (001), (111), (101), (122), and (212). Spectrographic analyses indicate a nearly end-member composition with Mo, Fe, Ba, Ca, and Mn present in trace amounts only. This stolzite fluoresces lemon- yellow and red in shortwave and longwave UV light, respectively.-G.W.R.