As from 1999, the area at Mana-Lisu was probably the most productive mine in Chaung-gyi valley. At the mine #21 (22°58'16''N. 96°31'18''E. 1,384 meters above sea level at the manager's hut), rubies and blue sapphires, mostly opaque and of low quality, were recovered from the alluvium using open-pit and myaw-dwin
mining methods. Most gems are suitable for cabochons and weigh below 5 carats. Transparent stones of fine quality are also found but they are rare, especially in large sizes. In the same area, star rubies, star sapphires, spinels and lapis-lazuli are also recovered from the alluvium. At the adjacent primary deposit, rubies and spinels are recovered from different types of marble.
Ref: Ted Themelis (2008) Gems & mines of Mogok, p. 186