Heulandite

specimen number:
1052758

location:
Lonavala Quarry, Pune, Maharashtra, India

description:

Attractive lustrous crystals of heulandite across the top of matrix. In good condition.

The Lonavala quarry complex, situated in the Pune District of Maharashtra, India, is a highly significant industrial aggregate and mineral locality renowned for its exceptional secondary zeolites and associated species. Geologically, the quarries cut directly into the thick, stacked basaltic lava flows of the Cretaceous to Paleocene-age Deccan Traps, where rapid cooling of the volcanic rock trapped expanding gases to form extensive networks of vesicles and larger geode cavities. Subsequent low-temperature hydrothermal fluids and circulating groundwaters leached silica, calcium, and aluminum from the surrounding basalt, precipitating highly pristine, specialized mineral assemblages featuring large crystals of apophyllite, scolecite, stilbite, and heulandite, typically hosted within a dark, fine-grained basaltic matrix. Historically, large-scale commercial open-cut quarrying operations began in the mid-to-late twentieth century to supply crushed basalt rock for major regional infrastructure projects, including the construction of local dams, railways, and the Mumbai-Pune Expressway. While the primary economic driver of the quarries remains the continuous extraction of industrial aggregate rather than systematic gemstone mining, the active blasting and mechanical rock-splitting operations have consistently exposed rich mineral-bearing pockets, supporting ongoing artisanal specimen recovery alongside heavy industrial operations through 2026.

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