Common types of volcanic rock

Common types of volcanic rock

Table
Common types of volcanic rock
name silica content (percent) major minerals colour approximate density with no voids (grams per cubic cm)
basalt 45-53 Ca feldspar, pyroxene, olivine dark gray 3.0
andesite 53-62 CaNa feldspar, pyroxene, amphibole medium gray 2.9
dacite 62-70 Na feldspar, amphibole, biotite, quartz light gray* to tan 2.8
rhyolite 70-78 K, Na feldspars, quartz, biotite light gray* to pink 2.7
*Obsidian glass can be dark gray to black.
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Universalium. 2010.

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