The area of Lay-tha-apya-taw (Blue Stone region) is situated north-east of Lay-tha-anee-taw
. The mining site at 1512 m. ASL, produces large quantities of blue sapphires. The majority of these sapphires are found in the mother rock and they are fractured and badly flawed. Some of them may be cut into low quality cabochons. Lay-tha-apya-taw is the only area in Mogok where gem quality topaz of natural blue color occurs. In the same area, schorl and moonstone are also found.
Ref: Ted Themelis (2008) Gems & mines of Mogok, p. 173