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PCS Earth Science
Chapter 5 Vocabulary - Igneous Rocks
Term | Definition |
---|---|
igneous rock | formed from the crystallization of magma |
lava | magma that flows out onto the Earth's surface |
extrusive rocks | fine-grained igneous rocks that cool quickly on Earth's surface |
intrusive rocks | coarse-grained rocks that cool slowly beneath Earth's surface |
partial melting | the process whereby some minerals melt at low temperatures while other minerals remain solid |
fractional crystallization | the process wherein different minerals more at different temperatures |
Bowen's reaction series | sequential, predictable, dual-branched pattern in which minerals crystallize from cooling magma |
felsic rocks | light-colored rocks that have high silica content and contain quartz and the feldspars orthoclase and plagioclase, low density |
mafic rocks | dark-colored rocks that have low silica content and are rich in iron and magnesium and have a high density |
ultramafic | igneous rocks with low silica content and very high levels of magnesium and iron, extremely dense |
porphyritic | rock texture characterized by large, well-formed crystals surrounded by finger-grained crystals of the same material |
pegmatite | vein deposits of extremely large-grained minerals that contain rare ores such as lithium and beryllium |
kimberlite | rare ultramafic rock that can contain diamonds and other minerals formed only under very high pressures |
geothermal energy | energy from steam or hot water produced from hot or molten underground rocks; energy derived from the heat in the interior of the earth |