Basalt rocks are extrusive mafic rocks, containing by weight less than 52% silicon oxide, the chemical composition corresponds intrusive gabbro, with dark color, mineral composition of labrado, pyroxene, olivine. Basalt is located in many areas in Vietnam, especially in the Tay Nguyen and the South. The weathering of basalt creates the red soil, red brown soil fertility or bauxite ore. Heated basalt stones may flow to cotton spinning glass, or cast as acid-proof materials.