Dacite
“The volcanic middle child”
Igneous
Dacite is an extrusive igneous rock with a composition between andesite and rhyolite. It's commonly found at stratovolcanoes and is associated with some of the most explosive eruptions in recorded history, including Mount St. Helens in 1980.
Composition
plagioclase feldspar, quartz, biotite, hornblende, pyroxene
Where Found
Cascade Range (USA), Andes Mountains, Mount Pinatubo (Philippines), New Zealand
Mohs Hardness
6-7
Fun Fact
The lava dome that grew inside Mount St. Helens after its 1980 eruption is made almost entirely of dacite.
Test Your Knowledge
Why is dacite particularly associated with the growth of lava domes inside volcanic craters?
Related Specimens
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