gems, jade, jadeite, jadeite, fei cui identification, quartz

Namiki examines four jade-like green ornamental stones reportedly discovered in upstate New York. The specimens consist chiefly of quartz: X-ray diffraction showed that both the white and green portions are predominantly quartz, with a small amount of calcite in the white portion and about 10% diopside in the green portion; microscopic dark-green grains were identified as chrome diopside. The material has refractive indices of approximately 1.543 and 1.550 and a specific gravity of about 2.65. Its vivid green color initially raised suspicion of dyeing, but spectroscopy showed chromium absorption lines at 680, 640, and 620 nm, while X-ray fluorescence confirmed chromium and a very small amount of nickel, with no detectable iron. Namiki therefore concludes that the material is naturally chromium-colored quartz rather than dyed quartzite; photographs and X-ray diffraction and fluorescence diagrams illustrate the specimens and analytical results.