Schallerite

A vein 6 mm thick of fine-grained, brownish-red schallerite cutting granular franklinite-willemite-calcite ore. The willemite is of orange-pink color, but the specimen is from Franklin, not Sterling Hill. Schallerite in this form is readily confused with friedelite, but XRF analysis revealed abundant arsenic in the vein and almost none in the adjacent matrix rock, confirming the ID. Additional confirmation was made by Raman spectroscopy. The history of this specimen can be traced back to Ewald Gerstmann, who correctly identified it as schallerite. It later entered the collection of Fred Howell, from whom the Franklin Mineral Museum eventually acquired it, relabeled it as friedelite, and offered it for sale (for $5!). It was purchased in 1992 by Earl R. Verbeek (his specimen ERV-2374), who later confirmed the schallerite by the methods mentioned above and in May 2020 donated it to the Franklin Mineral Museum, where it is housed as specimen FMM-2569.

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