Download SEDIMENTARY ROCK LAB

Lab Sedimentary Rocks
Rocks & Minerals
Name ___________________________
Date _______________
Hour _____
Pre-Lab Questions
1. What are the three sedimentary rock classification categories?
2. List the five steps of lithification and give a brief description of each step (from your notes).
Question Using the sedimentary rock samples, and the sedimentary rock identification key, can
you correctly identify 7 of the 10 samples on the first try?
Background Information
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Hypothesis
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Experiment
1. Obtain the Mineral & Rock Kit, glass plate, a tripod lens.
2. Use the materials and the chart on page 4 to identify each sedimentary rock sample.
3. Ask teacher to approve your samples and then, proceed to complete the data table and the
questions.
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Lab Sedimentary Rocks
Rocks & Minerals
Data Table
Sample
#
Name of
Sedimentary
Rock
Class
(Clastic,
Chemical or
Organic)
Mineral
Composition
Possible
Sedimentary
Environment
of Formation
Reacts
w/HCl
Scratches
Glass
16
25
55
56
57 / 18
58
61
62
63
65
Conclusion Questions
1. How are the particles that make up the conglomerate different from those that make up the
sandstone, or shale?
2. Look closely at the conglomerate sample. What minerals can you identify?
3. Why are fossils rare in conglomerate?
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Lab Sedimentary Rocks
Rocks & Minerals
4. How do the two limestone samples differ in appearance and in formation?
5. Sedimentary rocks are important to piece together the history of our planet, explain why.
6. Describe the process of lithification in the formation of sedimentary rocks.
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Lab Sedimentary Rocks
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Rocks & Minerals
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Lab Sedimentary Rocks
Rocks & Minerals
ANSWERS
Pre-Lab Questions
1. What are the three sedimentary rock classification categories?
Clastic Sedimentary rock 
rock fragments are carried away by wind, water or ice, and
deposited. These individual fragments become compacted
and cemented together into solid rock. Conglomerate,
breccia, shale, sandstone.
Chemical Sedimentary rock  minerals were once dissolved in water precipitated out (solid
in liquid). Gypsum, halite.
Organic Sedimentary rock  rock that forms from the remains of living things. Coal,
limestone.
2. List the five steps of lithification and give a brief description of each step (from your notes).
•
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•
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Weathering – Exposure
Erosion – transportation
Deposition – Different depositional environments
Compaction – Overlying layers of material decreases volume
Cementation – minerals work as glue for grains
Question Using the sedimentary rock samples, and the sedimentary rock identification key, can
you correctly identify 7 of the 10 samples on the first try?
Background Information
Classification of sedimentary rock is based on three main factors:
1. The chemical composition of the material that make the rock.
2. The biological (if any) composition of the material the rock is made of.
3. The physical environment that formed the rock.
There are three major depositional environments (part of lithification).
1) continental environment  lakes, streams, rivers, swamps and floodplains
2) transitional environment  coastal (in between marine and continental)
3) marine environment (ocean, salt water)  deep and shallow ocean environments
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Lab Sedimentary Rocks
Rocks & Minerals
Data Table
Sample
#
Name of
Sedimentary
Rock
Class
(Clastic,
Chemical or
Organic)
Mineral
Composition
16
Gypsum
Organic
CaSO4·2H2O
25
Dolomite
Clastic
CaMg(CO3)2
55
Fossil
limestone
Organic
Ca(CO3)
Thallus slopes,
juvenile streams
56
Coal
Organic
C
Swamps
Chemical
NaCl
Shallow
marine
Organic
Ca(CO3)
Deep oceans
57 / 18
58
Rock salt
(halite)
Chalk
limestone
Possible
Sedimentary
Environment
of Formation
Lake, sea
water
Geologic
record
Reacts
w/HCl
Scratches
Glass
powder
yes
yes
yes
61
Conglomerate
Clastic
Quartz, mica,
clay
Beach, rivers
62
Shale
Clastic
Clay
Lake, delta
63
Breccia
Clastic
Dolomite
Thallus slopes,
juvenile streams
yes
65
Sandstone
Clastic
Quartz,
feldspar
Beach, rivers
yes
yes
Conclusion Questions
1. How are the particles that make up the conglomerate different from those that make up the
sandstone, or shale?
Conglomerate has many particles sizes of different origins while sandstone and shale are
more regular in terms of particle sizes.
2. Look closely at the conglomerate sample. What minerals can you identify?
Feldspar, quartz, hornblende, calcite, mica
3. Why are fossils rare in conglomerate?
Conglomerate was formed in a turbid environment. Fossils need a calm, more stable,
environment to form.
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Lab Sedimentary Rocks
Rocks & Minerals
4. How do the two limestone samples differ in appearance and in formation?
Chalk  white … formed in the deep ocean
Limestone  tan … formed in shallow, marine environments
5. Sedimentary rocks are important to piece together the history of our planet, explain why.
Sedimentary rocks are where most of the fossils form because it preserves the remains of
ancient plants and animals.
6. Describe the process of lithification in the formation of sedimentary rocks.
Lithification is the process of rock formation that occurs when rock material (any type of
material) is exposed to the environment.
• This is known as weathering.
• Once the rock is weathered, it can be transported; this is known as erosion.
• Weathering (breaking down of rock material) and erosion (transportation of this rock
material) are the first steps in the lithification process.
• The following are all ways that material can be transported (eroded) in the process of
forming sedimentary rocks: Wind, Water, Ice, Gravity.
• Then, based on transportation of the minerals, deposition takes place.
• Eventually, minerals are compacted and cemented into rocks.
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