This is an incredibly interesting specimen, with a history. The uncanny blue you see here in this thin seam is a little-known hydrous arsenate of copper; a secondary mineral of copper and arsenate deposits. It is in combination here with erythrite, which surrounds the lavendulan and continues around the specimen as a seam; the lavendulan is basically sandwiched by the erythrite. Hey's Mineral Index lists lavendulan from this locality as being described by one E. Goldsmith in 1877 at the Proceedings of the Academy of Natural Sciences in Philadelphia. Ex. Philadelphia Academy of Natural Sciences Collection.