This issue’s quarterly crystal is a gem-quality very light pinkish brown topaz (figure 1) from the Dusso mine in Pakistan. The transparent singly terminated topaz crystal measures 30.52 × 29.84 × 27.89 mm and weighs 216.56 ct. It hosts a prominent 6 mm long dark brownish orange phlogopite mica booklet that shows strong brownish orange and yellow dichroism as well as lamellar cleavage planes (figure 2).
A tiny cluster of dark brownish red manganotantalite and colorless albite inclusions are also present. Small near-colorless and transparent mica and feldspar inclusions are randomly scattered throughout the crystal. This suite of inclusions strongly suggests that a complex granitic pegmatite was the parent rock type of this topaz.
John I. Koivula is an analytical microscopist at GIA in Carlsbad, California.
This issue’s quarterly crystal is a gem-quality very light pinkish brown topaz (figure 1) from the Dusso mine in Pakistan. The transparent singly terminated topaz crystal measures 30.52 × 29.84 × 27.89 mm and weighs 216.56 ct. It hosts a prominent 6 mm long dark brownish orange phlogopite mica booklet that shows strong brownish orange and yellow dichroism as well as lamellar cleavage planes (figure 2).
A tiny cluster of dark brownish red manganotantalite and colorless albite inclusions are also present. Small near-colorless and transparent mica and feldspar inclusions are randomly scattered throughout the crystal. This suite of inclusions strongly suggests that a complex granitic pegmatite was the parent rock type of this topaz.
John I. Koivula is an analytical microscopist at GIA in Carlsbad, California.
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