Prehnite after Laumontite with Fluorapophyllite-K

specimen number:
2062405

location:
Pathanwadi Quarry, Malad, Mumbai, Salsette Island, Konkan, Maharashtra, India

description:
An attractive loose cluster of what were once prismatic laumontite crystals, these now replaced by light green crystallized prehnite. Colorless gemmy sparkling micro crystals of fluorapophyllite are scattered throughout. In great condition. Classic material for this locality. Okenite is present as well.

The Pathanwadi Quarry, located in Malad on Salsette Island within Mumbai (formerly Bombay), Maharashtra, India, is part of the extensive Deccan Traps basaltic formations of the Konkan region. While exact individual opening and closing dates for this specific quarry are not precisely documented in historical archives, stone and mineral quarrying operations across the Salsette group were heavily active from the mid-19th century through the mid-20th century to supply construction materials and to uncover rich secondary mineral assemblages from basalt cavities.

A pseudomorph forms when one mineral replaces another or assumes its crystal shape. In the specific case of prehnite after laumontite found in these regional quarries, early-formed prismatic crystals of laumontite acted as a structural template and were overgrown by prehnite. When the internal laumontite later dissolved or weathered away, it left behind hollow or solid shells of green prehnite that perfectly preserved the original crystal morphology of the laumontite.

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