Htan-yan-sho, Pein-Pyit (Painpyit; Pyan Pyit), Mogok Township, Pyin-Oo-Lwin District, Mandalay Region, Myanmar
This mining area was known before the 1970s. It is situated about 8 km from Mogok town, between Dattaw in the north-east and Pein-pyit village in the south-west. It is close to Mogok-Momeik road, forming a natural basin where many gems have accumulated. Another mining area is situated at the base of a marble faulted scarp in contact with garnet-bearing gneiss; leucogranite rocks and several skarns are also known in the same area. For many years gems have been mined in the loos (loo-dwin) situated in the adjacent hill.In 2001 these mines produced mostly spinels (60%), near-colorless, greenish-blue, purple and other colored sapphires (10%), rubies (5%), other gemstones (25%). In 2004, most gems mined were blue or blue/green sapphires, fewer of fine quality; also some rubies. Other gems found iclude quartz, tourmaline, moonstone, near-colorless to yellowish and greenish chrysoberyl, danburite, topaz, zircon, diopside, fibrolite, amblygonite/montebrasite and andalusite. Vivid green grossular suitable for cutting brilliant gems below 2 carats were also recovered.
Most of the gems are found in sandy byôn using open-pit mining methods. Blue and blue-green sapphires, some milky-silky are also found in the alluvium and they are similar to those found at Pyant-gyi. Some of these sapphires are suitable for heat-treatment to enchance their color and increase their transparency. Rubies and spinels are found in the adjacent primary marble deposits.
Ref: Ted Themelis (2008) Gems and Mines of Mogok, p. 192