This igneous rock contains large amounts of iron, chrome, and feldspar. I know it contains a large amount of feldspar, because it makes a white streak when scratched against a steel file. Basalt is a grey to black rock. When basalt is broken (if at all possible) it makes a conchidal fracture. I know that basalt is a Mohs-6-7, because it scratches glass but is scratched by steel. Basalt is formed by a volcano that erupts and spews out lava that is rich in iron and magnesium but low in quartz. The lava cools quickly and forms fine-grained basalt.
Links
Home Page
Granite
Peridotite
White Granite
