We recently examined a 57.56 ct rock crystal quartz (figure 1) that came from Luciana Barbosa (Gemological Center, Asheville, North Carolina). Said to be from Bahia, Brazil, the transparent and colorless rectangular step-cut gem measured 31.91 × 19.01 × 11.83 mm and hosted two relatively large translucent euhedral crystals. When examine under magnification, these inclusions appeared to be hexagonal prisms, the larger one measuring approximately 7.0 mm in length. Rotation of the microscope’s analyzer clearly displayed the crystals’ dichroism, which changed from blue to pale yellow (figure 2). Laser Raman microspectrometry was used to identify the inclusions as chlorapatite. This is the first time that we have encountered chlorapatite as a inclusion in quartz.

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John I. Koivula is analytical microscopist at GIA in Carlsbad, California.

John I. Koivula

Koivula, GIA