The gem deposit is located in a deep elongated natural marble fissure, long known for its dangerous loos (twisted holes) and caves. This natural fissure is more than 800 meters long and varies in width from ~60 to 100 meters. The fissure runs approximately in a N-NW direction, and is situated at the bottom of the mountain ridge along the Bawpadan road.
By April 1999 the number of mines had fallen considerably, mining became unprofitable. In November 1999 there were only 11 plots in the main fissure, other plots in the adjacent area continued gem mining and by 2002 there were still in operation. In the following years gem mining became more difficult.
A combination of gwè-dwin
and tunelling methods are used to reach the gem-bearing marble bands lying at the bottom of the crevice. The marbles are light green, light blue and yellowish white, lenticular-shaped and usually associated with sphene, scapolite, diopside and pyrite. Ruby
, star ruby
are found in the loos (twisted holes - loo-dwin
) mixed with gravel and soil.
Ref: Ted Themelis (2008) Gems and Mines of Mogok, p. 224