basalt

A fine-grained basic igneous rock occurring in dykes, sills and lava-flows; essential minerals are plagioclase felspar and augite. Dark grey to black in colour; relative density 2.8-3.3; aggregate crushing value 7-25.

[img_assist|nid=14486|title=Basalt|desc=Basalt being blasted|link=none|align=left|width=346|height=200]