Earth Science Quiz 05/04/18
The four igneous rocks below are classified into two groups. What's the basis for this classification?
Crystal grain size.
Rock B most likely is...
Peridotite.
Which two igneous rocks can have the same mineral composition?
Gabbro and basalt.
A coarse-grained rock contains 50% plagioclase, 45% pyroxene, and 5% hornblende. According to the Earth Science Reference Tables, this rock should be identified as...
Gabbro.
The obsidian rock's glassy texture indicates that it formed from a magma that cooled...
Quickly, on Earth's surface.
Which two rocks most likely formed farthest below the surface of Earth?
A and B.
Which relative concentrations of elements are found in a felsic rock?
A high concentration of aluminum and a low concentration of iron.
Larger crystal size in one of two igneous rocks of similar composition usually indicates that the rock with the larger crystals cooled for...
A longer period of time than the other.
A fine-grained igneous rock composed mostly of plagioclase feldspar and hornblende (and containing no quartz or pyroxene) would be classified as...
Andesite.
A fine-grained igneous rock contains 11% plagioclase, 72% pyroxene, 15% olivine, and 2% amphibole. This rock would most likely be classified as...
Basalt.
The table below provides information about the mineral composition of a sample of beach sand from Hawaii. If the sand deposited on this beach recently weathered from only one type of igneous rock, the rock was most likely...
Basalt.
According to the Earth Science Reference Tables, rhyolite and granite are alike in that they both are...
Felsic.
Some Moon-rock samples have coarse intergrown crystals composed of plagioclase feldspar, Hornblende, and olivine. These Moon-rock samples are most similar to Earth-rock samples of...
Gabbro.
Which characteristic of rock B could be caused by the minerals pyroxene and olivine?
Green color.
Which property is common to most dark-colored igneous rocks?
High density.
Rock X and rock Y are igneous rocks with identical mineral composition. Rock X has no visible crystals and rock Y large, visible crystals. What can be inferred about Rock Y?
It cooled beneath the Earth's surface, more slowly than rock X.
According to the Scheme for Igneous Rock Identification, compared to basalt, granite is...
Lighter in color.
Olivine and pyroxene are commonly found in igneous rocks that are...
Mafic, low density.
Most igneous rocks form by which processes?
Melting and solidification.
According to the Earth Science Reference Tables, rhyolite is an example of a...
Polymineralic igneous rock.
Which minerals are present in granite but are never present in gabbro?
Potassium feldspar (orthoclase) and quartz.
A fine- grained rock has the following mineral composition: 50% potassium feldspar, 26% quartz, 13% plagioclase, 8% biotite, and 3% hornblende. The rock would most likely be...
Rhyolite.
The mineral, quartz, in rock A is composed of the two most abundant elements by mass in Earth's crust. These two elements are oxygen and...
Silicon.
Which graph best represents the relationship between the length of time molten magma takes to cool and the size of the crystals in the rock formed by the magma?
The graph that's increasing.
According to the Earth Science Reference Tables, which statement is true of granite and gabbro?
They're both intrusive.
