Massive white gypsum cementing altered clasts of granular franklinite-willemite-calcite ore. Gypsum in this form is readily mistaken for calcite by the unwary, but its inferior hardness is an easy way of distinguishing them. Formerly belonging to Ewald Gerstmann and later part of the SPEX Industries (Art and Harriet Mitteldorf) collection, this is now specimen FMM-750 of the Franklin Mineral Museum.
Identifier: GYP2a Locality: Sterling mine, Ogdensburg, NJ Specimen size: 16 x 10 x 7.5 cm (face shown measures 14.5 x 7 cm) Photo credit: Earl R. Verbeek
