Prehnite after Laumontite

Unknown Owner

Prismatic crystals of what were once laumontite to 3.0 cm in length now replaced by green crystallized prehnite. Some damage present, still a nice example for this Indian classic.The Kandivali Quarry, located in the Mumbai suburban district of Maharashtra, India, is a significant mineral locality situated within the massive basaltic flows of the Deccan Traps. Geologically, the site is composed of tholeiitic basalt containing numerous vesicles and cavities where secondary hydrothermal mineralization produced a variety of zeolites and related silicate minerals. The quarry is specifically renowned for its remarkable prehnite pseudomorphs after laumontite, where light green to yellow-green prehnite replaced the original prismatic laumontite crystals, often preserving their distinct diamond-shaped cross-sections and terminated forms. Historically, mining and quarrying at Kandivali were primarily driven by the massive demand for basalt as road ballast and construction aggregate for the expanding Mumbai metropolis. While small-scale extraction occurred earlier, the most productive period for mineral specimen recovery was during the mid to late 20th century, particularly between the 1960s and 1980s. As of 2026, many of the original quarrying sites in this urbanized area have been closed or reclaimed for residential development, making these specific prehnite pseudomorphs highly prized as classic historical specimens from a now largely inaccessible location.