mimetite

Yellow, gemmy, mimetite prisms (to 18 mm) growing on either side of a shard of matrix (which itself appears to be a mat of smaller, densely intergrown mimetite crystals). Most of the yellow prisms have been overgrown by a second generation of off-white mimetite resulting in some club-shaped terminations and off-white composite sheaves enclosing the prism faces of the original crystals but, interestingly, leaving many of the original terminations clear.

This specimen is from the collection of Mark Feinglos (#3727), who purchased it from Julius and Miriam Zweibel in May 1976.

(not assigned)