The students have been learning to classify rocks by the main types of igneous, sedimentary and metamorphic. They have to look at the composition and texture of the rocks very carefully to decide the sub-types within each of these groups and then to identify those rocks by name. We have rock guides to help them do that, but they need to apply all of the vocabulary that they are learning about the texture and composition as each type of rock has a different vocabulary for those concepts. They have to break the rocks with hammers in order to see an unweathered and uneroded surface of that rock to have a more detailed look at what that rock is like. They can then use the microscopes to see the grain and the particles at the microscopic level to accurately know what the composition truly is, the macroscopic level is not always a true indicator of the composition.
We do various other things to help with identification and give us more information about the composition, such as acid tests to know if there is any reaction going on that would tell us if there is any organic matter in the rock. The students have also had lessons on the techniques needed for secure handling of the rocks, the steps they need to break the rocks safely and effectively. They wear protective goggles and space themselves out while they are outside, they also use a large stone as a base and can use two hammers to brace the rock as they hit it.
“This project is about rock collection. We’re studying sedimentary, igneous and metamorphic rocks and it’s a lot of fun because when you break the rock you can go and look at it under the microscope to study it and draw it. You can see the particles under the microscope and that helps you know which rock you have got.” Alix
By Robert Taub, MS Science Teacher