In the Sagyin Hills, just 26 km north of Mandalay and 3.2 km from the Irrawaddy river, rubies were once obtained from the detritus of clay-filled hollows and fissures in the crystalline limestones.
Ref.:
http://www.ruby-sapphire.com/r-s-bk-burma4.htm6 entries listed. 3 valid minerals.