Windmills in Rare Mineral Sphalerite
Sphalerite is a rare gem mineral that crystallizes in the cubic crystal system and consists largely of zinc sulfide formed with variable iron, with the chemical formula of (Zn,Fe)S. Its color is usually yellow, brown, red, or gray to gray-black with high dispersion and high adamantine luster. The author recently examined a high-quality faceted orange sphalerite weighing 47.56 ct that revealed three-ray structures reminiscent of windmills with each propeller arm separated by 120°. Additionally, the orange color was concentrated in the immediate region of the three radial arms of each propeller-like structure (see above). Other typical internal characteristics of sphalerite such as strong angular internal growth with orange color zoning, particulate clouds, tiny crystals, and fingerprints, were also observed. This distinctive structure resembling windmills is the first such feature the author has encountered in sphalerite.
