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Mohs Hardness Test

Geology MatchCard

Let's Have Some Moh Fun

We will use the Mohs Hardness Test to identify rocks and minerals. This is the fifth lesson in the MatchCard Science Geology Unit Study for 3rd to 8th graders.

mohs hardness test

Mohs Hardness Test MatchCard

Objective: Apply Moh's test to identify the hardness of minerals.

MatchCard: Download below.

MatchCard Information Pieces describe the different steps of Mohs Test. Ideas for projects are listed on the instructor's page and below.

How Moh's Hardness Test Works

Moh's Hardness is a scale from 1 to 10 listing minerals from the softest (1) to the hardest (10).

A rock or mineral can only be scratched by an object with a higher ranking on the scale. Therefore, if you know what a mineral is, you can use it to help identify the hardness of other minerals. That will help identify the mineral itself.

There are also other common items such as glass, steel, copper, and even fingernails, that can be used in place of other minerals to identify the hardness of a particular rock or mineral.

Use A Moh's Kit

Mohs Hardness Test Activity #1

You can either buy a Moh's Kit, or make one buy acquiring ten specimens of common minerals.

The most commonly used minerals are:

10. Diamond
9. Corundum
8. Topaz
7. Quartz
6. Feldspar
5. Apatite
4. Fluorite
3. Calcite
2. Gypsum
1. Talc

Most kits, whether purchased or made, do not have a diamond, which is the hardest level. Of course, you can always borrow someone's wedding ring to do this test. However, for students one can probably perform tests with specimens 1 through 9 and get the point across without using a real diamond.

To perform the test, give the students the minerals without any identification. They must see what minerals will scratch the other minerals.

By trial and error, the students arrange the specimens in order of hardest to softest.

Identify Unknown Specimens

Mohs Hardness Test Activity #2

After students have performed the first test, they can now use the known minerals to identify the hardness of unknown minerals.

Give the students 5 to 6 specimens of other rocks and minerals. Let them experiment to identify the hardness on the Mohs Scale.

Once the hardness is identified, let them use a rock guide to see if they can find the name of their specimen.

If a rock is being tested, once it is found in the field guide the student should also identify if it is a Igenous, Sedimentary, or Metamorphic rock.

Use Common Tools

Mohs Hardness Test Activity #3

For this final rock identification activity, we will use common tools instead of known specimens.

If you purchased a kit, they might have been included. Here are the items needed:

Fingernail
Copper penny
Steel knife (does not need to be sharp)
Steel file
Glass (pocket sized mirror will work)

In addition you will need a variety of rocks and minerals. You may use the specimens used in the previous activity. (Unless they have already memorized the identify of the specimens.)

With the assortment of specimens, they start at the bottom test of hardness (fingernail), and if it does scratch the surface of the rock, they move to the next hardest test.

10. The hardest mineral
9. Can only be scratched by a diamond
8. Rock can scratch glass
7. Rock can scratch steel
6. Scratched by a steel file
5. Scratched by a steel knife
4. Easily scratched by a knife
3. Scratched by a copper penny
2. Scratched by a fingernail
1. Easily scratched by a fingernail

Again, it is helpful to check your rocks and minerals field guide to verify the correct specimen.

Download and Use the Mohs Hardness Test MatchCard

This is the fifth Matchcard of the Geology Unit Study. You can DOWNLOAD the
Mohs Hardness Test Matchcard HERE.

The student matches the description of the rock hardness test with the number on the table.

The second page is the Instructor's Guide with the correct answers.

The third page has the Information Pieces. Student's cut them apart and place them in the correct place on their copy of the Matchcard (first page.)

For more information on how to use the Matchcards, see the MatchCard Science Instructor's Guide.

More information on this interactive unit study is below.

MatchCard Science

The activities and illustration above are from MatchCard Science, a homeschool science unit study. For the complete Geology Unit Study follow this link. This unit study provides:

hands-on demonstrations
MatchCard reviews to master the material
suggestions for science projects to complete
instructions on a complete unit study curriculum

Currently this curriculum is under-going revision. We are providing free access to the unit study, with the desire that you will provide feedback as you are field testing the materials.

Return from Mohs Hardness Test MatchCard to the MatchCard Science Main Page.

The Kid Friendly Homeschool Curriculum HOME PAGE.