Topaz

Imperial topaz has been a classic mineral variety for collectors due to its special orange to cherry red to even purple color, Cr3+ plays an important role in the coloration of pink to form those long-term classics in Pakistan.

These are found in calcite, quartz(not too much), muscovite veins crosscutting the Silurian or Devonian gray limestones, where probably the source of Cr., temperature of crystallization was about 230 °C during the Eocene Himalayan tectonothermal event. Interestingly, these topaz growth from Low-F, CO2-rich metamorphic fluid. Al buffering by mica prevented fluorination of carbonates and stabilize topaz, so you may not see fluorite in that area.

Katlang, Mardan District, Khyber Pakhtunkhwa Province, Pakistan

Jeff Scovil photo