Natrochalcite is a very rare hydrated, sodium, copper sulfate the and the Chuquicamata Mine of Chile is the Type Locality. Discrete, gemmy and lustrous, emerald-green natrochalcite crystals to 6 mm richly and attractively cover the porphyry matrix. This very fine old-time specimen has an approximately 100-year old A.E. Foote label glued to the bottom of the piece.