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.
List at least 1 rock that you identified in the lab that is a felsic igneous rock.
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)
-Porphyritic (two distinct grain sizes)
-Pegmatitic (extremely course grained)
Sort these ingneous rocks, first by texture, then by minerology.
-Diorite, Basalt, Gabbro, Granite, Rhyolite, Andesite, Obsidian, Peridotite,
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
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.
List at least 2 rocks that you identified in the lab that are intrusive igneous rocks.
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;
List a least 2 physical distinctive characteristics of the igneous rock Obsidian.
Define 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.
Engineering Geology - Chapter 3 - Igneous Rocks
CHAPTER 3: Igneous Rocks, Intrusive Activity, and the Origin of Igneous Rocks. TOPICS: The Rock Cycle, Igneous Rocks, Identification of Igneous Rocks, Intrusive Bodies, Plutonic Rocks, How Magma Forms, How Magmas of different compositions form.