What categories can Igneous rocks be divided into based on
Mafic: abundant dark-colored ferromagnesian minerals (e.g., gabbro, basalt). Intermediate: contain roughly equal amounts of dark and light colored minerals (e.g., diorite, andesite) Felsic: contain abundant light-colored minerals (e.g., granite, rhyolite).
How would you distinguish, on the basis of minerals present, between granite, gabbro, and diorite?
Granite would have more SiO2 (silica, quartz) than Gabbro. Granite is felsic and lighter colored - more white and pinkish. Gabbro would have more ferromagnesian minerals than Granite. Gabbro is mafic and darker colored - may be greenish. Diorite would have roughly equal amounts of these minerals. Diorite is intermediate and is black and white looking, like salt and pepper,
List at least 1 rock that you identified in the lab that is a mafic igneous rock.
Possible Answers:gabbro; basalt; peridotite.
List at least 1 rock that you identified in the lab that is a felsic igneous rock.
Possible Answers: granite; rhyolite.
What are the two main ways in which igneous rocks are classified?
Name the different possible textures of Igneous rocks, in order from smallest grain size to largest.
-Glassy (no grains) -Aphanitic/Fine grained -Porphyritic (two distinct grain sizes) -Phaneritic/Course grained -Pegmatitic (extremely course grained)
Sort these ingneous rocks, first by texture, then by minerology.
-Diorite, Basalt, Gabbro, Granite, Rhyolite, Andesite, Obsidian, Peridotite,
Glassy Texture: Mafic: Obsidian
Aphanitic/Fine Grained: Felsic: Rhyolite Intermediate: Andesite Mafic: Basalt
Phaneritic/Course Grained: Felsic: Granite Intermediate: Diorite Mafic: Gabbro, Peridotite (peridotite can also be listed as ultramafic)
What is the difference between a dike and a sill?
A dike is an intrusive body that cuts across the layers in the country rock. A sill is an intrusive body that layered in with the layers in the country rock (parallel).
The major difference between intrusive igneous rocks and extrusive igneous rocks is:
A. where they solidify
B. Type of minerals
C. Chemical composition
D. All of the preceding
A. where they solidify
Which is not an intrusive igneous rock?
By definition, stocks differ from batholiths in
c. Chemical composition
d. All of the preceding
What is the difference between instrusive and extrusive igneous rock?
Extrusive igneous rocks cool quickly at or near Earth’s surface and are typically fine grained. Instrusive igneous rocks cool slowly deep beneath Earth’s surface and are typically coarse-grained.
The most common igneous rock of the continents is
List at least 2 rocks that you identified in the lab that are extrusive igneous rocks.
Possible Answers: rhyolite; andesite; basalt; obsidian; pumice; etc.
List at least 2 rocks that you identified in the lab that are intrusive igneous rocks.
Possible Answers:granite; diorite; gabbro; peridotite
How would you distinguish andesite from a diorite?
Based on grain size. Andesite is a fine grained (intermediate) rock, while Diorite is a coarse grained rock
What grain size is used to distinguish between course-grained and fine-grained igneous rock?
1mm. Course-grained rocks have grains greater than 1mm, and fine-grained rocks have grains equal to or less than 1mm.
List a least 2 physical distinctive characteristics of the igneous rock Pumice.
Possible Answers: fibrous; light colored; porous; lightweight
List a least 2 physical distinctive characteristics of the igneous rock Obsidian.
Possible Answers:glassy; black, massive (non-porous)
Geothermal Gradient. What is the average geothermal graidient of Earth's crust?
Geothermal gradient is the rate at which temperature increases with increasing depth beneath the Earth surface. In the upper part of the crust, temperature increases at an average 3 degrees C for each 100 meters, or 30 degrees C per km of depth.