The old mining area has been known since the times of the Burmese kings. The largest mining scheme commenced operations in July 1992 and in 2000 was still open.
Rubies,
spinels and fewer blue
sapphires of all qualities are found in the soft alluvium. The stones are recovered using
lebin and open-pit mining methods.
Ref: Ted Themelis (2008) Gems and Mines of Mogok, p. 220
Gemstone List