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Chapter 3

Concept #3 Quiz

Concept #3 Quiz
Choose the best possible answer to the following questions about Key Concept 3 "Compositions of igneous rocks and their meaning."

This activity contains 10 questions.

	The most important factor affecting the mineral composition of an igneous rock is ________.   chemical composition of the magma or lava amount of space available for crystals to fill pressure rate of cooling

	Which are definitions of “mafic” and “felsic”?   a. Mafic is a magma/rock that is rich in feldspar and silica (quartz), whereas felsic refers to that which is rich in Fe and Mg. b. Mafic is a magma/rock that is rich in Fe and Mg, whereas felsic refers to that which is rich in feldspar and silica (quartz) c. Mafic is hard rock, felsic is soft rock. Both a. and c. None of these.

	Mafic rocks/magmas are ________, whereas felsic rocks/magmas are ________.   dark colored, more dense and less viscous (not sticky); light colored, less dense and more viscous (sticky) dark colored, less dense and more viscous (sticky); light colored, more dense and less viscous (not sticky) light colored, less dense and more viscous (sticky); dark colored, more dense and less viscous (not sticky) striped and dotted; solid and pinstriped

	What type of composition would result in a magma if equal amounts of basaltic and granitic magma were mixed?   andesitic granodioritic gabbroic rhyolitic

	What type of composition would result in a magma if basaltic and granitic composition magma were mixed completely at a 1 to 3 ratio?   andesitic gabbroic rhyolitic granodioritic

	What composition magma is beneath the Mt. St. Helens volcano, and why?   felsic – very sticky magma makes for explosive eruptions intermediate – the intermediate range composition magma makes for strato volcanoes that are mostly passive erupting basaltic – very sticky magma makes for very passive (fluid) eruptions mafic – very fluid magma makes for passive (fluid) eruptions

	Which one of the following rock types contains the greatest amount of quartz?   basalt granite komatiite gabbro andesite

	Which of the following rocks is likely to have the most quartz within it and why?   basalt; extrusive rock that formed from cooling of relatively low silica lava rhyolite: extrusive rock that formed from cooling of relatively low silica magma granite; intrusive rock that formed from cooling of relatively high silica magma basalt; extrusive rock that formed from cooling of relatively high silica lava diorite; intrusive rock that formed from the cooling of relatively intermediate silica magma granite; intrusive rock that formed from cooling of relatively intermediate silica magma

	Match the volcano with the appropriate rock formed by its eruption. Using the pull-down menus, match each item in the left column to the corresponding item in the right column. ocean ridge volcanoes Kilauea volcano, Hawaii Mt. St. Helens volcano, Washington state Andes mountains volcanoes 9.1 basaltic scoria A B C D 9.2 porphyritic andesite A B C D 9.3 rhyolitic pumice A B C D 9.4 pillow basalt A B C D

	__________ composition lava is erupted at ocean ridges, whereas ____________ composition lava is erupted on continents.   basaltic, rhyolitic gabbroic, rhyolitic gabbroic, granitic basaltic, gabbroic

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