Home > Type Localities I – June 9 > MS1090 Sinkankasite
Sinkankasite - Sold
- Barker-Ferguson mine
- Keystone
- Pennington County
- South Dakota
- U.S.A.
- 3.2 by 2.2 by 2.1 cm – Thumbnail specimen (fits into a 2.5 cm cube)
Sinkankasite is a hydrated manganese aluminum phosphate mineral (Peacor et al. 1984). The mineral name honors U.S. Navy Captain John Sinkankas (1915-2002), who took up mineralogical and gemological studies after retiring, and writing several books including Mineralogy, Gemstones of North America, and Emerald and Other Beryls. Sinkankasite forms colorless needles in two places on this specimen, including a 3 mm long spray in one cavity. The matrix is granitic pegmatite consisting mostly of quartz and muscovite.