Euclase after Beryl

specimen number:
9711770

location:
Last Hope Mine, Mwami, Karoi, Mashonaland West, Zimbabwe

description:
Prismatic crystal of what was once of beryl, this now replaced by blue euclase. In good condition all around.

The Last Hope Mine, located near Mwami in the Karoi District of Mashonaland West, Zimbabwe, is a small working historically known for producing rare mineral specimens rather than large-scale industrial output. Exact opening and closing dates are not formally documented, but operations have occurred in intermittent spurts from the 1960s onward. Geologically, the mine is situated within complex pegmatite formations associated with regional metamorphic and intrusive rocks, where hydrothermal activity and chemical alteration facilitated the formation of beryllium-bearing minerals alongside quartz, mica, and topaz.

Pseudomorphs of euclase after beryl occur when chemical solutions alter an original beryl crystal, replacing its chemical structure with euclase while retaining some external shape or form. At the Last Hope Mine, these pseudomorphs typically present as crude, massive fragments or partially replaced crystals where the euclase has taken over the precursor beryl template. Although discrete, well-formed euclase crystals are exceptionally rare and valuable, the pseudomorphous material provides crucial insight into the secondary replacement processes occurring within these complex pegmatite pockets.

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