Mohs hardness scale worksheet pdf

Minerals – Hardness of Unknown Minerals Note: you must do the “Introduction and Mohs Hardness Scale” lab before doing this lab since some of your results from that lab are needed to complete this one! For this lab, you will test the hardness of unknown minerals by interacting with a website developed by a geology professor, David J. Leveson, with photographs by Guillermo Rocha, both from Brooklyn College. This site discusses mineral properties and testing procedures and also provides an opportunity for you to practice testing minerals. Make sure to read all of the information provided on each specified webpage as you attempt to answer the questions. I recommend that you print this lab to keep track of your answers, and then use those to input your answers into our online class site so that you can then get credit for the laboratory exercise. Determine the Hardness of Unknown Minerals Using your knowledge of Mohs Hardness Scale, you will now determine a numerical value for the hardness of assigned unknown minerals (specimen #s 1, 2, 4, 5, 10, 11, 13, 14, 15, 16, 17, 19, 20 and 22). The hardness of any mineral can be determined by figuring out which two minerals the unknown mineral lies between on Mohs Hardness Scale. For example, imagine that an unknown mineral is scratched by quartz, but is not scratched by orthoclase. Instead, the unknown mineral scratches the orthoclase. Since quartz has a hardness of 7, and orthoclase has a hardness of 6, our unknown mineral would have a hardness of 6.5. It is also possible for a mineral to have a hardness exactly that of the hardness of one of the Mohs Minerals. In that case, they will not scratch each other, and the hardness of the unknown will be a whole number equal to that of the hardness of the Mohs mineral. Knowing the hardness of an unknown mineral is often useful in identifying it. For example, apatite and beryl are often very similar in appearance. However, they have very different hardness. Apatite has a hardness of 5, while beryl has a hardness of 7.5 to 8. Therefore, a simple hardness test can help distinguish them. Directions Step 1: On the data table below, enter the specimen number for each of the minerals of Mohs Hardness Scale, which you determined in the “Introduction and Mohs Hardness Scale” lab. Step 2: Go to this website: http://academic.brooklyn.cuny.edu/geology/leveson/core/graphics/hardsim/hard_sim6x.ht ml Step 3: Select one of the unknown minerals from “List #1” (on the website). You will see it show up under the yellow box in picture form. Step 4: Select a mineral from Mohs Hardness Scale from “List #2” (on the website). You will see it show up under the Yellow box in picture form. Remember that from the “Introduction and Mohs Hardness Scale” lab, the minerals of Mohs Hardness Scale have an asterisk (*) next to them. You also determined the names for each of those asterisked minerals in that lab. Step 5: Push the “Scratch” button under the pictures. Does the Mohs Hardness Scale Mineral scratch the unknown mineral? If it does, enter “yes” on the data table.” If it doesn’t, enter a “no” on the data table. However, if neither mineral gets scratched in the process, they are the same hardness, so write “equal” on the data table. Step 6: Repeat this process with the same mineral from “List 1” but this time, select a different Mohs Hardness Scale mineral from “List #2.” Record the results of the hardness test (a yes, no, or equal) in the data table. Step 7: Determine between which two Mohs Hardness Scale minerals the hardness of the unknown specimen falls, or if it is equal in hardness to one of the Mohs Minerals. Remember, if neither the unknown mineral or the Mohs mineral gets scratched during the test, then they have the same hardness. Otherwise, it falls between two hardness values, and the difference can be split. For example, specimen #16 is scratched by #6* (calcite, which has a hardness of 3) and all harder minerals of Mohs Hardness Scale. However, it is not scratched by (and instead scratches) #12* (gypsum, which has a hardness of 2) and all softer Mohs minerals. Therefore, the hardness of specimen #16 is between a hardness of 2 and 3, resulting in a hardness of 2.5. Step 8: Repeat the above steps for each of the unknown minerals.