Schallerite

A vein of type I schallerite, with a maximum preserved thickness of 2.3 cm, on a matrix of gneissic, high-grade, willemite-franklinite zinc ore.  The visible surface is a fault (note striations) that cuts obliquely through the earlier schallerite vein. Some of the schallerite, as seen here, is granular, opaque, and vuggy, but that nearer the vein contact is microcrystalline, slightly translucent, and reddish-brown in color, similar to the schallerite in specimens SCH3 and SCH10.  The willemite in the ore immediately adjacent to the vein is locally bleached to an orange-tan color (the fresh material is green) and is nonfluorescent, dull-lustered, and pervaded by microvugs.  This specimen, with catalog number FMM-7830, was donated to the Franklin Mineral Museum in late 2017 by Sharon Orosz in memory of her husband Joe, former FMM curator and an astute collector of the local minerals.  Additional labels show it had two previous owners before entering the Orosz collection.  The schallerite has been confirmed both by XRF data (which revealed abundant arsenic in the vein material) and by Raman spectroscopy.

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