BROOKITE ON QUARTZ

ABOUT THE SPECIMEN

A large number of razor sharp brookites right on top of clear quartz, presenting in a super nice arrangement from multiple angles. On the display side the quartz is in excellent condition. Many of the brookites are chipped (brooken?) though the coverage more than makes up for it in my eyes.

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Zard Mountain - "Yellow Mountain" in Baluchi - is part of the Ras Koh ophiolitic complex, the same serpentinized peridotite terrane responsible for the district's brucite and epidote, with brookite here forming in hydrothermal veins and fractures cutting the mafic and ultramafic host rocks at relatively low temperatures. Brookite is the orthorhombic polymorph of titanium dioxide, metastable at surface conditions relative to rutile, and crystallizes specifically from low-temperature hydrothermal fluids in weakly acidic to neutral pH environments - the Ras Koh ophiolite providing both the titanium source and the fracture permeability necessary for open-cavity growth. The locality first produced significant material around 2004, operated by the Nausherwani family whose name is attached to the primary producing workings; exact pocket locations remain deliberately undisclosed. Crystals are tabular to pseudo-octahedral pseudohexagonal prisms with a distinctive fiery red color deepening toward the terminations - a chromophore mechanism involving iron impurities - and occur as isolated individuals or divergent clusters on quartz matrix, sometimes with anatase and faden quartz as associates. Pakistan has substantially displaced Switzerland and the Magnet Cove Arkansas occurrence as the dominant source for collector-grade brookite over the past two decades, and Zard Mountain material in particular represents the finest large-crystal expression of the species known.