- nhung khoang san chu yeu la: dau mo , khi dot , than, sat , crom , kim loai mau
-+ dau mo: truong giang ,BD an do , bien ARAN, ....
+ Khi dot : D. DAGROT, dong bang Tay Xibia....
+than: S.Obi , truong giang, SN . Decan ....
+sat: song hang , truong giang ,day URAN......
+ crom : song an , D. luxon, ....
( chuc bn hok tot )