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Scoria is a dark-colored extrusive igneous rock with abundant round bubble-like cavities
From late Middle English (denoting slag from molten metal), from Greek skōria refuse, from skōr dung
Durable Rock, Medium Hardness Rock
Fine Grained Rock, Opaque Rock
Rhomb-porphyry is a porphyritic igneous rock with abundant wedge or lens shaped anorthoclase or feldspar phenocrysts
From Latin term that means purple
Durable Rock, Medium Hardness Rock
Fine Grained Rock, Opaque Rock