Name ______________________________ Date__________________ Period ______
Activity 16 - Mineral Identification
Objective: Students will be able to identify an unknown mineral sample by comparing it
to known properties of known minerals, without error, on the first try.
Problem: Jake went hiking in the Grand Canyon. While hiking, he came across two types
of minerals: calcite and quartz. Jake placed all the calcite and quartz samples in the
same bag. However, he forgot to label which one was which. Jake now needs help
determining which minerals are calcite and which are quartz.
Hypothesis: If we test the hardness of an unknown mineral and the hardness is a three
on the Mohs Scale, then the mineral is calcite, because calcite’s hardness is a three on
that particular scale.
Materials:
 Unknown mineral samples
 Copper strips
 Glass scratch plate
 White ceramic streak plates
 30-mL bottles of 0.5M hydrochloric acid
 Cups of water
 Magnifying lenses
 Safety goggles
Procedure:
1.) The unidentified mineral is either calcite or quartz. Examine the table below and
discuss with your lab partner which properties will be the most useful in
identifying the unknown mineral. If you think the property is useful, place a star
in the blank box next to the property. You will choose four properties to test.
Table 1:
Useful? (*)
Property
Transparency
Luster
Hardness (Mohs Scale)
Calcite
Colorless, white, pink, red,
green, blue
Translucent
Dull
3
Quartz
Colorless, white, pink, purple,
blue, yellow
Transparent
Glassy
7
Streak color
Reaction with acid
White
Small bubbles, fizzing
White
No reaction
Color
2.) In Table 2, write down the four properties that your group chose to test under
the heading property in the column at the left.
Table 2:
Property
Observation
**** Remember, please use complete sentences when writing your observations. ****
3.) Put on your safety goggles now and do not take them off until the end of the lab.
4.) Observe the transparency of the unknown mineral. Is the mineral transparent,
translucent, or opaque? Write down your observation of the unknown mineral in
your data table (Table 2).
5.) Observe the luster of the unknown mineral. Is the mineral brilliant, glassy, or
dull? Write down your observation of the unknown mineral in your data table.
6.) Place the unknown mineral in your hand. Attempt to scratch it with your
fingernail. Does it scratch? If it does write down that it has a hardness of one (1)
in your data table.
7.) Now try to scratch the copper strip with the mineral. Does the mineral scratch
the copper? If it does scratch copper, write that it has a hardness of three (3) in
your data table. If it does not scratch the copper, write that it has a hardness of
one (1).
8.) Next, rub the mineral across the glass plate. Does it scratch the glass? If your
mineral does scratch the glass, write down that it has a hardness of seven (7) in
your data table. If it does not scratch the glass, say that it has a hardness of five
(5).
9.) ***Be careful with the acid. Do not get it onto your clothing, hands, or
anywhere near your eyes. If you get it on your hands, be sure to wash your
hands.*** Place two drops of acid onto the unknown mineral; do you see
bubbles coming out of the mineral? Write down your observations in your data
table.
10.)
After placing acid on the mineral, carefully place the mineral into the cup
of water. Let it rinse for a few seconds, then pull out the mineral and place it onto the
paper towel.
11.) Compare your observations in Table 2 to what we know about each mineral in
Table 1. Based on your observations, what mineral is your unknown sample?
My unknown mineral 1 is ______________________________________.
Conclusion/Analysis Questions
Directions: Read each question carefully, and then answer the questions using complete
sentences.
1.
Which properties did you decide to test? Why did you choose these properties?
2.
Did everyone in your group have the same data for each property of the unknown
mineral? Why or why not?
3.
What was the unknown mineral? How did you know what mineral the unknown
was?
4.
Support your mineral identification with at least four pieces of evidence from your
investigation. Be sure to compare your laboratory results to properties of both
calcite and quartz. (4-6 sentences minimum)
5.
Jewelry is made from many different minerals. Would you prefer to buy jewelry
made of calcite or quartz? Explain your answer using information from this activity.
(3-5 sentences minimum)