Download Rock Identification Lab

Key to Rock Classification
First use the key below to identify the possible type for each rock sample. When you have it narrowed down to a specific
type such as igneous, sedimentary or metamorphic, use the additional keys to determine the name of the specific rock.
1. Does the rock contain visible connecting crystals
Yes: Go to question 2
No: Go to question 4
2. Are all of the crystals/grains the same color and
shape?
Yes: The rock is a non foliated metamorphic rock (possibly
marble or quartzite)
No: Go to question 3
3. Are all of the crystals in a mixed “salt and pepper”
pattern?
Yes: The rock is an intrusive igneous rock (possibly granite
or diorite)
No: The rock is a foliated metamorphic rock (possibly
schist or gneiss)
4. Is the rock glassy? (does it resemble broken glass)?
Yes: The rock is an extrusive igneous rock (obsidian)
No: Go to question 5
5. Does the rock have flat thin layers that can be
broken apart?
Yes: The rock is a foliated metamorphic rock (slate)
No: Go to question 6
6. Does the rock contain many small holes or have a
uniform dark color?
Yes: The rock is extrusive igneous rock (possibly pumice,
scoria or basalt)
7. Does the rock contain pebbles, sand, or smaller
particles that are cemented together?
No: Go to question 7
Yes: The rock is a clastic sedimentary rock( possibly
conglomerate, sandstone, shale or breccia)
8. Does the rock fizz when dilute HCl is dropped on
it?
No: Go to question 8
Yes: The rock is a chemical or organic sedimentary rock
(limestone, chalk, coal, coquina)
No: Ask your teacher for assistance
Sample #
Description (color, grain size, gain
Route to
Group Identification (include
shape, banding, holes, weight,
identification
intrusive, extrusive, foliated, non
luster)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
foliated, clastic, organic)
Rock Name
Follow-Up Questions:
1.
How does the rock cycle explain the formation of igneous, metamorphic, and sedimentary rocks?
2.
How is the formation of these three types of rocks related to each other?
Igneous Rocks
1.
Which of the rocks identified would be considered intrusive?
Describe the properties of intrusive igneous rocks.
2.
Which of the rocks identified would be considered extrusive?
Describe the properties of extrusive igneous rocks.
Metamorphic Rocks
1.
Which of the rocks identified would be classified as foliated?
How did they become foliated?
2.
Which of the rocks identified would be classified as nonfoliated?
What happens to the minerals in these nonfoliated rocks?
Sedimentary Rocks
1.
Which of the rocks identified would be considered clastic sedimentary rocks?
How do the sediments in the clastic rocks become solid rock?
2.
Which of the rocks identified would be considered chemical sedimentary rocks?
How might this chemical rock have formed?
3.
Which of the rocks identified would be considered organic sedimentary rocks?
How might these organic rocks have formed?