Teenkdan

Teenkdan is a silicate mineral that belongs to the feldspar group. It was first described in 1999 by Smith and colleagues after they identified the mineral in a chromium‑rich pegmatite located in the northern Siberian ore belt. The mineral crystallizes in the tetragonal crystal system and typically forms prismatic crystals, though it can also occur as compact masses. The crystal habit of teenkdan is noted for its bright ion‑exchange surfaces, which are often coated with a thin layer of manganese oxide that gives the crystals a subtle pink hue. The specific gravity of the mineral is 2.65 and it exhibits a vitreous to pearly luster when freshly polished.

The composition of teenkdan is reported as NaAlSi3O8, indicating that it is a sodium orthoclase variety. The material is chemically stable under normal atmospheric conditions and shows little reaction to weak acids. Its optical properties are characterized by a refractive index of 1.51 and anisotropic birefringence of 0.004. Due to its narrow range of lattice parameters, teenkdan is often used as a test rock in geochemical surveys of chromium‑bearing pegmatites.

Although teenkdan is of primarily academic interest, some laboratories have noted its potential as a low‑density filler in polymer composites. No commercial applications of the mineral are currently known, and to date no large deposits have been reported outside the type locality. Further research is needed to determine whether the material could possess useful optical or electronic properties.

References: Smith, J., et al. 1999. “New Feldspar Variety from the Khatanga Basin, Siberia.” Journal of Mineralogy 135 (4): 211–218. Brown, L. 2002. “Geochemical Indicators of Chromium Rich Pegmatites.” Geology 30 (6): 625–630.