Where to Find Datolite in New Jersey

New Jersey datolite is a classic Triassic basalt mineral from the Watchung Mountains of Passaic, Bergen, and Essex counties. Paterson and Prospect Park quarries produced pale-green-to-yellow datolite as glassy prismatic crystals in basalt amygdules, often with prehnite, pectolite, calcite, and quartz associations. The Bergen Hill cuts (long built over) yielded the famous datolite specimens of the 19th century. Active and recently active trap-rock quarries (Great Notch, Upper Montclair, Summit) continue to surface specimens through club access. Datolite is fragile and brittle, so wrap individual crystals and avoid acid cleaning that attacks the calcium-borate composition.