igneous
Scoria (Lava Rock) and Granite
Vesicular Basalt (Scoria) and Monzogranite
Scoria: Hardness 5-6, black to dark grey, dull luster, highly vesicular/porous, fine-grained. Granite: Hardness 6-7, pink/tan/white, phaneritic (coarse) crystal structure, contains quartz, feldspar, and mica.
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Physical properties
Scoria: Hardness 5-6, black to dark grey, dull luster, highly vesicular/porous, fine-grained. Granite: Hardness 6-7, pink/tan/white, phaneritic (coarse) crystal structure, contains quartz, feldspar, and mica.
Formation & geological history
Scoria forms from gas-rich basaltic magma cooling rapidly near a volcanic vent. The granite boulder is an intrusive igneous rock formed by slow cooling of magma deep underground, likely from the Precambrian or Paleozoic era.
Uses & applications
Scoria is used for landscaping, gas grills, and drainage. Granite is used for construction, monuments, and decorative boulders.
Geological facts
Scoria is so full of holes it is extremely lightweight, though unlike pumice, it usually sinks in water. The granite boulder shows weathering typical of glacial transport or long-term exposure.
Field identification & locations
Identify scoria by its 'sponge-like' appearance and dark color. Granite is identified by its visible interlocking crystals of different colors. These are common in residential landscaping.
