Jamesonite is a not a common mineral. It has been found in many of the famous arsenic-rich
hydrothermal replacement deposit
ore localities. It was first described from Cornwall, England, where this mineral had occurred in several localities, especially St. Endellion. Fine hairy Jamesonite masses were found at Příbram, Bohemia, Czech Republic; and rounded crystal masses from the Herja Mine, Baia Mare, Maramureș Co., Romania. The Herja Mine has also produced a rare form
Calcite colored dark gray from dense Jamesonite
inclusions. The Yaogangxian Mine, Yizhang Co., Hunan Province, China, produces large masses of feathery Jamesonite crystals associated with
Quartz.
Large crystal masses of Jamesonite of excellent quality have come from the San José Mine, Oruro Bolivia. In Mexico, fine hairy masses are known from the Noche Buena Mine, Mazapil, Zacatecas; and aggregates of unusually thick crystals have come from Concepción del Oro and Sombrerete, Zacatecas.
In the U.S., Jamesonite needles interwoven with
Quartz crystals have come from the Daly-Judge Mine, Park City District, Summit Co., Utah; and parallel masses were found in the Coeur d'Alene district, Shoshone Co., Idaho.