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Geology Science Fair Project

Rock Hardness Challenge

Rock Hardness Challenge | Science Fair Projects | STEM Projects
Have you ever wondered how geologists tell the difference between rocks? With this fun science project, you can become a rock expert and learn how to classify rocks by their hardness!


The hypothesis is that rocks of different compositions have different levels of hardness, and that the Mohs Scale can be used to classify and compare their relative hardness.

Method & Materials

You will test different rocks and minerals progressively with a fingernail, penny, iron nail, and steel file to see which object was able to make a scratch on the rock or mineral. Then compare the object that was able to make a scratch to the Mohs Scale to determine the rock or mineral's hardness level.
You will need samples of different rocks and metals, as well as an old copper penny, an iron nail, and a hardened steel file.


After conducting the "Rock Hardness Challenge," it was observed that different rocks and minerals have different levels of hardness. It is interesting to note that some rocks, such as granite, are much harder than others, like talc, which can be easily scratched with a fingernail.

Why do this project?

This science project is interesting because it teaches you how to use the Mohs Scale to test the hardness of rocks and metals. It also shows how geologists and miners use the Mohs Scale to classify and compare different minerals in their work.

Also Consider

Experiment variations could include testing the hardness of different types of rocks or metals, or testing the effects of different pressures or angles on the scratching process. Another variation could be testing the hardness of different household items using the Mohs Scale.

Full project details

You can find additional information and details for this science fair project here. Have fun exploring!

Related video

Hey there! Here are some awesome videos about this science project that we think you'll really like. They're not only super fun, but they'll also help you learn more about the science behind the project. So sit back, relax, and get ready to have some fun!!
Discover the history of the Mohs hardness scale and learn about the ten rocks and minerals that are ranked from softest to hardest! Can you guess which rock is the softest and which one is the hardest? Let's find out!
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