calcite after mimetite (?) (w. conichalcite-duftite)

Hollow, tube-like structures composed of white, rhombohedral calcite crystals and apparently epimorphous after mimetite (?), are richly encrusted (on the outer surfaces) with radiating aggregates of bright-green acicular microcrystals of conichalcite-duftite (XRD verified). The tube structures are completely hollow, with all traces of the original mimetite (?) removed (exhibits 2 and 3). Locally, the conichalcite-duftite is overgrown with a brown layer of dolomite with green tangeite microcrystals (XRD verified; Exhibit 2). A single crystal of dioptase (circa 2 mm) is visible at the extreme bottom right of the specimen (as seen in Exhibit 1).

The location in the mine from which this specimen was recovered is not recorded, but it is almost certainly from the second oxidation zone.

conichalcite-duftite; dioptase; dolomite; tangeite