| Basalt is a fine-grained, dark-coloured, dense rock which
has a dull, granular appearance. Basalt, the volcanic equivalent of gabbro, is often porphyritic.
Commonly basalt is vesicular, that is, it has holes (vesicles) which were once gas
bubbles; later, these holes often fill with mineral matter (amygdules). Basalt which
formed by underwater eruptions charateristically develop rounded pillow-like shapes.
Basalt is a very common rock in British Columbia. |
