This Acanthite Update features excellent specimens of well-crystallized acanthite (pseudomorphs after argentite) from the Imiter Mine, in Ouarzazate Province, Morocco. The Imiter Mine is Africa’s largest silver mine, with workings dating back to the 8th century A.D.

Acanthite (pseudomorph after argentite) – 5.0 cm

Well-crystallized acanthite has never been common and most of the known localities for crystals are historic, making it difficult and usually expensive to obtain fine specimens. The finds at Imiter in recent years have placed it among the world’s best ever localities for crystallized acanthite. Given the relative scarcity of high quality well defined acanthite crystals over the history of mineral collecting, it is reasonable to assume that the Imiter mine acanthites will be classics.

Acanthite (pseudomorph after argentite) – 6.3 cm

Although these crystals formed as argentite, argentite is not stable below 179C, at which point it changes to monoclinic acanthite. The specimens are acanthite pseudomorphs after argentite, retaining the isometric crystal form of the original argentite crystals.

Acanthite (pseudomorph after argentite) – crystal 2.8 cm

I assembled this lot of acanthites over a period of about two years. Most of these specimens, from the 2008 find, remained in Morocco until 2013.