Home > Laskowski Ⅶ – August 10 > MS1929 Pharmacosiderite


Pharmacosiderite is a hydrated potassium iron arsenate, and the namesake for the pharmacosiderite supergroup (Rumsey et al., 2010). Although known for decades under other names, including "cube ore", German mineralogist Friedrich Hausmann renamed this mineral Pharmakosiderit in his 1813 Handbuch der Mineralogie. The mineral name persists in its anglicized version, pharmacosiderite. The name combines the Greek roots pharmacos and sideros, for poison (implying arsenic) and iron, respectively. Early authors gave varying compositions, but crystal structure solution by Zemann (1948) indicated essential potassium. Pharmacosiderite exchanges cations in solution and its water content varies, much like zeolites (Buerger et al., 1967; Mutter et al., 1984).

Pharmacosiderite here forms green cubes to 2 mm on brecciated quartz rock. These historic specimens date to the nineteenth century; they are rarely seen on the mineral market. From the collection of E.R. Laskowski (1949-2020), a mining engineer who retired to Tucson, Arizona.

Price: $625

Item code: MS1929

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