Download Lab 5.1: Igneous Rock Identification ( /25) COARSE FINE

Name: ____________________________________ Block: __________ Date: ______________________
EARTH SCIENCE 11
Lab 5.1: Igneous Rock Identification (
/25)
Objective:
1. To become familiar with examples of the two great classes of igneous rocks.
2. To understand how the texture (mineral size) of an igneous rock is related to origin.
Materials:
Set of igneous rocks
Igneous rock description sheet
Procedure:
1. Work in groups of two.
2. Get rock samples 1 to 9.
3. Divide the samples into two groups. Take out the “weird” rock samples and set them aside.
The rocks to take out are: the “Frozen milkshake” rock with honeycomb holes, the “Styrofoam
rock” that will float in water, the black glassy smooth rock, and the “chocolate chip cookie” that
has white chunks in a dark matrix rock. Set these aside for now.
Looking at your remaining 5 rocks…
4. For each rock, record its color (i.e. black; light pink; mixture of light pink with black spots).
Record on the observation table.
5. For rocks 1-4, identify the minerals present and underline the most common mineral.
6. For each rock, record its texture. It if has large crystals, then its texture is coarse; if the crystals
are small, then its texture is fine; etc. Record on the observation table.
7. For each rock, record its igneous rock type. A plutonic rock is formed at depths and cools
slowly forming large crystals (coarse texture). A volcanic rock forms on the surface as lava cools
quickly forming microscopic crystals (fine texture). Sometimes gas causes bubbles to form in the
lava as it solidifies. Record on the observation table.
COARSE
FINE
Granite
Diorite
Rhyolite
Basalt
Gabbro
8. Using the Percentage of Minerals in Igneous Rocks chart, arrange the 3 coarse grained rocks
above the chart using minerals present and then color index. Name the rocks and record them
on the observation table.
Name: ____________________________________ Block: __________ Date: ______________________
EARTH SCIENCE 11
9. Arrange the 2 fine grained rocks below the chart using the color index. Name the rocks and
record them on the observation table.
Looking at the 4 “Weird Rocks”…
10. Put aside the 5 rocks you just identified and bring back the 4 “weird rocks”.
11. Complete steps 4 – 7, then using the descriptions and chart on the rock description sheet
identify the rocks. Name the rocks and record them on the observation table.
Observation Table A: Igneous Rocks (18 marks)
Mineral
Number
1
Color
Minerals Present
2
3
4
5
n/a
6
n/a
7
n/a
8
n/a
9
n/a
*Table marks: 2 mks/sample
Texture or
Mineral(s) size
Igneous Rock Type
(Plutonic/Volcanic)
Rock Name
Name: ____________________________________ Block: __________ Date: ______________________
EARTH SCIENCE 11
Questions: (5 marks)
1.
In mineral sample 1, what mineral is mainly responsible for the pink color?
______________ ___________________
2. Samples 5 and 6 both formed by rapid cooling of magma. How they differ is with their
mineralogy. Which sample do you think contains the light colored minerals such as quartz and
K-feldspar? (Give the name, not the number.) __________________________________
3. If the coarse grain rocks such as granite form deep within the earth, what geologic events
occurred to bring the rock to the surface? Explain.
4. How does sample 8 get the air bubbles to form? Explain.
5. Pyroclastic rocks is the term for material blown out of a volcano. Extremely hot (500⁰C +) and
fast (150 km/h) flows of this material has cooked and buried many a human. Which sample is
welded ash? (Give the name, not the number.) __________________________________
Conclusion: (Answer the objectives) (2 marks)
a)
The two classes of igneous rocks are _______________________________________________
b) Coarse texture rocks (a.k.a. ________________________) form __________________________.
Fine texture rocks (a.k.a . ________________________) form ___________________________.
* On task behavior (-10 marks first time, zero on lab second time).