An exceptionally rich, old-time specimen of the rare sulfate, krohnkite, from the Type Locality, the Chuquicatmata Mine of Chile. The piece is beautifully complimented by the rare, emerald-green sulfate, natrochalcite. Chuquicamata is also the Type Locality for natrochalcite. Without question, this specimen exhibits the most intense teal blue color I have ever seen in a natural mineral specimen and has great translucence. And the variation in blue color, in itself, is very noteworthy. The veins exhibit what is classic for the species, lamellar growth of crystals in parallel bundles. The piece was purchased on September 11, 1939. Ex. Harvard and George Elling Collections.