Eye Pattern in a Rock Fragment

Ching Yin Sin and Piradee Siritheerakul

Recently, the authors encountered a partially polished rock fragment measuring 14.50 × 9.43 × 2.43 mm and weighing 3.45 ct that exhibited a very realistic eye pattern (see above). Various shades of yellow and green material formed the pupil and iris, while a distinctive white outline surrounded the iris as a sclera. Microscopic observation revealed different microcrystalline minerals. Raman spectroscopy identified pyroxene, feldspar, and quartz as the most abundant minerals. Energy-dispersive X-ray fluorescence (EDXRF) analysis revealed silicon as the dominant element, while traces of iron and potassium were also detected.

Naturally formed eye patterns in gems are rare but do exist, such as a “dragon’s eye” in a fire agate (Winter 2015 G&G Micro-World, p. 441) and a radial eye structure in a sapphire (Summer 2017 G&G Micro-World, pp. 244–245). While the textures in rocks are much more diverse than those in single-mineral gemstones, observing such a unique feature is always exciting.