Testing the hardness of a rock can help you determine what type it is.
In 1822 a scientist named Friedrich Mohs invented what is now known as the Mohs test or the scratch test--the most commonly used test to determine the hardness of rocks and minerals. This test is important for identifying unknown rocks and minerals. Basically, the test compares the hardness of rocks and minerals to a set scale, which runs from softest to hardest, in order to identify what a specimen is. The test is based on the fact that a harder rock will scratch a softer one.
Instructions
1. Select the rock you want to test and find a clean spot on it.
2. Scratch your rock specimen with an object of known hardness. Some common objects you can use include a penny (hardness of 3.0), your fingernail (hardness of 2.5), and a knife (hardness of 5.5). You can also use any of the minerals listed on the Mohs hardness scale. Once you see a scratch on your rock specimen, you will know your rock is softer than the object that scratched it.
3. Write down the hardness levels of the objects that scratch your rock specimen. You are looking for the object with the lowest hardness level. Then you will know the approximate hardness level of your rock and will be able to identify it by using the Mohs scale of hardness.
Tags: your rock, rock specimen, rocks minerals, your rock specimen, hardness level, hardness rocks
