On-line Sedimentary Rock Identification Lab
http://facweb.bhc.edu/academics/science/harwoodr/Geol101/Labs/Sediment/
Part 1:
a. Go to the website above.
b. You will need to read each section in order to complete the questions below.
c. It will be necessary for you to click on each underlined word. This will provide you
with a complete explanation and illustration of each key term.
d. All questions must be completed correctly prior to moving on the Part 2.
1. How is sediment deposited?
Sediment is deposited in numeral environment through out the world, by moving air and
water.
2. What is sedimentary rock identification based on?
It’s based on the rocks composition.
3. In this lab, what does “texture” mean?
Texture is the sediment, chemical and biological substances that make up the rock.
4. What are the 3 types of texture?
1. Gravel
2. Calcite
3. Caron
5. What are “clasts?”
Clasts are fragments, pieces of rock or minerals.
6. How are chemical sedimentary rocks identified?
By identifying the mineral from which they are composed.
7. What are the 4 minerals that need to be identified in order to classify a sedimentary
rock?
1.
2.
3.
4.
Quartz
Halite
Gypsum
Calcite.
8. How do “biological” rocks form?
They form as the result of the accumulation of organic material or biologic activity.
9. What is an obvious characteristic of coal?
The dark brown to black color is the most obvious characteristic.
10.Coquina and limestone are both composed of the same mineral. What is it?
Calcite
11.What is the difference between coquina and limestone?
Almost entirely shell and skeletal fragments.
Part 2:
a. At the bottom of the web page you will find a link saying “select a sample to identify.”
b. You will need to identify each of the 12 sedimentary rocks shown.
c. As you identify the rocks, mark your answers to each category: texture; grain size;
composition; and rock name on the following pages for each of the 12 rocks.
d. There are hints given on each one including reaction to HCl, hardness, and more
detailed images – use them!
Texture
1
Grain size
4
5
6
7
None
Calcite
limestone
biologic
none
Coquina
Chemical
none
Calcite, almost
entirely shell and
skeletal fragments
Gypsum
biologic
none
Fossiliferous
Limestone
Clastic
<1/16mm
calcite with some
shell and skeletal
fragments
quartz, clay
minerals
Clastic
>1/16mm
feldspar, quartz
Arkrose
Chemical
none
gypsum
Rock gypsum
Clastic
>2mm
Conglomerate
Chemical
none
rounded quartz,
feldspar and rock
fragments
silica (quartz)
8
9
Rock Name
Chemical
2
3
Composition
Rock Gypsum
Siltstone (mud,
shale)
Chert
10
11
12
clastic
1/16-2mm
Quartz, feldspar
Sandstone
clastic
1/16-2mm
Quartz feldspar
Sandstone
biologic
none
densely compacted
organic
material and plant
fragments
Bituminous Coal