Lay-bauk (Wind Entrance) is situated on a steep slope east of the Mogok-Panlin road, with panoramic view of the Mogok valley. The mines at Lay-bauk are situated near the foothills of Taung-me, the highest mountain in Mogok. The general area is characterized by marbles, calc-silicate rocks, gneiss, contact zones and skarns.
Blue sapphires and spinels are mined from the alluvium. Most of these stones are opaque and of low quality, some suitable for cabochons. Better quality blue sapphires of faceting grade and spinels are occasionally found, but they are small in size, usually below two carats. A primary marble deposit in the nearby area produces small size rubies of low to medium quality of cabochon grade. In the skarn, rubies associated with feldspar, and apatite associated with spinel are found.
Ref: Ted Themelis (2008) Gems & mines of Mogok, p. 180