azurite

dolomite (?); malachite; quartz

Two pairs of parallel-grown azurite crystals, with each pair at circa 90 degrees to the other. The main crystal (98 mm) is double terminated. From one side (Exhibit 1) the azurite appears reasonably clean, with only minor and localised alteration to malachite. The other side of the specimen (Exhibit 2) has a duller lustre dues to incipient but widespread alteration. The crystals are attached to a shard of matrix consisting largely of rhombohedral dolomite (?) with minor quartz.

The specimen was formerly in the collection of Austrian industrialist Hans von Karabacek, part of which was purchased by Harvard University in 1935, thereby dating it unequivocally to the first oxidation zone.