Rock Classification
Igneous Rocks
Work through the activities in either of the following links before you attempt the exercises below.
http://www.classzone.com/books/earth_science/terc/content/investigations/es0603/es0603page01.cfm
1. Describe the 4 igneous rocks shown.
Samples
Description
1
2.
3.
4.
2. Identify the texture of each igneous rock as coarse grained, fine-grained or porphyritic.
Sample 1
Sample 2
Sample 3
Sample 4
Sample 5
Sample 6
3. Identify cooling rates (1. fast, slow, 2-staged) and cooling environment (2. magma chamber,
eruption from volcano, or deep cooling after eruption)
Sample 1
Sample 2
Sample 3
1.
1.
1.
2.
2.
2.
Sample 4
Sample 5
Sample 6
1.
1.
1.
2.
2.
2.
Rock Classification
Examine the digital samples of igneous rocks by clicking on the name of each rock. Use your observations
to complete the table below:
Rock sample
Andesite
Basalt
Diabase
Diorite
Dolerite
Gabbro
Granite
Obsidian
Rhyolite
Scoria
Color light or dark
Crystal size - large,
small or invisible
Cooling rate - slow,
fast or very fast
Intrusive or extrusive