Scoria is a dark-colored extrusive volcanic rock with abundant large vesicles. It commonly forms as a bubble-rich upper surface on many basalt and andesite lavas.
Texture: aphanitic and vesicular (contains abundant large gas cavities)
Composition: intermediate (andesitic) to mafic (basaltic)
Color: black or dark brown
Cooling Rate: rapid, extrusive
Intrusive Equivalent: diorite or gabbro
Other Characteristics: vesicular like pumice, but denser and darker with larger vesicles.
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