Abstract
In the Phong Điền area, Thừa Thiên Huế Province, black clay shale of the Long Đại Formation (O3-S1 lđ) has been recognized that it has the capacity of making additive materials for cement production, replacing basalt, the former material. Nowadays, two mineral bodies with relatively large scale have been evaluated. Chemical analysis and technical experiments showed that this black clay shale fully satisfies all technical requests of current National Standards TCVN 6882-2001 for using as additive materials of cement production. This is the newest source of materials for cement production of the province, which needs to be investigated and evaluated in the coming time, aiming to confirm its values.