Download Igneous Rocks Lab

Name:
Period
Igneous Rocks Lab
Background:
Igneous rocks are classified based on their mineral content and their texture. The
rock color is a simple indicator of the mineral content. The dark colored rocks are
rich in the metallic minerals that contain a high percentage of iron and
magnesium. These dark colored igneous rocks are referred to as mafic. The
lighter colored igneous rocks are rich in the quartz and feldspar minerals and are
referred to a felsic. The rock texture will be used to help determine the process
by which the rocks were formed. There are four terms used to describe texture.
Coarse grained refers to visible crystals that are larger than a grain of sand. Fine
grained refers to crystals that are smaller than a grain of sand. Whether or not a
rock appears glassy or has holes will also be used to describe an igneous rock’s
texture.
Directions:
1. Obtain one of the igneous rock samples from the front of the room. Make
sure you note its name and number!
2. Observe the rock, and carefully draw a picture of it in the appropriate box.
3. Write down any observable qualities that will help you identify it (color and
texture). Decide if the rock is extrusive or intrusive, and if it is felsic or
mafic.
4. Repeat this procedure until you have finished with all of the rock samples.
5. Answer the following analysis questions.
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Rock Sample #1
Name:
Color:
Texture:
Extrusive
or Intrusive
Mafic or Felsic
Rock Sample #2
Name:
Color:
Texture:
Extrusive
or Intrusive
Mafic or Felsic
Rock Sample #3
Name:
Color:
Texture:
Extrusive
or Intrusive
Mafic or Felsic
Igneous Rocks Lab
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Rock Sample #4
Name:
Color:
Texture:
Extrusive
or Intrusive
Mafic or Felsic
Rock Sample #5
Name:
Color:
Texture:
Extrusive
or Intrusive
Mafic or Felsic
Rock Sample #6
Name:
Color:
Texture:
Extrusive
or Intrusive
Mafic or Felsic
Igneous Rocks Lab
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Rock Sample #7
Name:
Color:
Texture:
Extrusive
or Intrusive
Mafic or Felsic
Analysis Questions:
1. Which rock is mafic and coarse grained?
2. Which rock is mafic and fine grained?
3. Which rock is felsic and coarse grained?
4. Which rock is felsic and fine grained?
5. Which rocks were formed inside a volcano?
6. Which rocks were formed outside a volcano?
Igneous Rocks Lab
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Igneous Rocks Lab
7. Using your data, complete the following comparison chart – use color,
texture, extrusive/instrusive, or mafic/felsic for your comparisons.
Gabbro
Basalt
Gabbro
Granite
Granite
Rhyolite
Rhyolite
Basalt
Scoria
Pumice
Similarities
Differences
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