1. BIG IDEA: Rocks and minerals have properties that can be: observed, tested, described, identified and recorded.

2. o What does the object look like? o Where have you seen it before? o What is it used for? o What do you think it is?

3. Mr. Maxwell came by to see how you were coming with identifying his rocks and mineral collection. He was very impressed with the data you recently collected for the luster test and hopes you will be able to identify all of his collection since many appear to have similar properties Today we are going to use more of the information and materials provided by our geologist to test the hardness of each mineral. A geologist will often use a Mohs Scale of Hardness to help identify and compare minerals. What does the principal and geologist want us to do? What did the geologist give us to help? What is the problem in this investigation?

4. How can we …

5. A volunteer will assist me with a simple demonstration. The volunteer will scratch the tip of a nail against a piece of chalk. Do you think the nail will scratch the chalk, or will the chalk scratch the nail? Which object is harder; the chalk or the nail?

6. I think that we can…because…

7. Hardness The resistance of the surface of a mineral to scratching by another substance. Mohs Scale of Hardness A scale that ranks the hardness of minerals compared to the hardness of other materials.

9. How can mineral hardness be used as a tool for identification? Do you think this test alone will help us identify all of our minerals? Explain your thinking. Why did we not test the rocks from our collection?