azurite (w. cerussite, malachite, otavite and smithsonite)

cerussite; dolomite (?); malachite; otavite; rosasite (?); smithsonite

A feldspathic sandstone matrix, covered with a sub-botryoidal layered carbonate crust comprising a layer of white dolomite (?), a thin layer of pale green smithsonite and a surface coating of pearly-white otavite (EDS confirmed. Frank Keutsch, Harvard University, 2025). Resting on the dolomite are slender prismatic crystals of azurite (to 50 mm). These have been completely replaced by malachite and then partly overgrown by lustrous second generation azurite (Exhibit 3). Non-pseudomorphous malachite spherules (to 1 mm), are richly scattered on the dolomite, while twinned, colourless cerussite crystals (to 5 mm) are more sparsely distributed. Many of the malachite spherules appear partly altered to rosasite (?) but this has not been confirmed.

Both the otavite and the cerussite fluoresce intensely under short wavelength ultraviolet radiation; the otavite yellow-orange, and the cerussite orange (Exhibit 4).

The specimen was number 4023 in the collection of Austrian industrialist Hans von Karabacek, part of who’s collection was purchased by Harvard University in 1935 which dates the specimen unequivocally to the first oxidation zone.