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Heulandite

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A pearly lustrous sharp crystal of heulandite in a cluster with several smaller crystals. In good condition. Excellent thumbnail for the species and locality. Complete all around. The Upper New Street Quarry, located on Garret Mountain in Paterson, Passaic County, New Jersey, was a historically significant stone quarrying operation famous among mineralogists for its diverse secondary zeolite and mineral assemblages. Geologically, the quarry cut directly into the triassic-aged Orange Mountain Basalt, a massive volcanic lava flow within the Newark Basin sequence. As the basalt cooled, trapped volcanic gases formed numerous pocket-like vesicles and structural fractures that were later filled by low-temperature hydrothermal fluids, precipitating high-quality crystals of prehnite, datolite, pectolite, and various zeolites like apophyllite and heulandite. Formalized quarrying for road metal, railroad ballast, and construction aggregate began at the site in the late nineteenth century to support rapid urban development in the New York metropolitan area. The quarry operated heavily from approximately 1890 through the late 1920s, with active industrial operations ceasing around 1930 as municipal expansion and environmental zoning restrictions forced its closure, after which the locality was eventually incorporated into the surrounding county park system.