Color is one of the most widely used processes of determining the classification of rocks. Some rocks are all one color and some contain many different colors Streak tests are another way of classifying different rocks. When you do a streak test you use a porcelain streak plate and the rock that you are trying to classify. By rubbing the rock against the plate it should leave a colored streak on the plate. You can classify the rock by the color of the streak that the rock left on the plate.
Some rocks have a magnetic quality.
Since there are very few rocks that are actually magnetic you can narrow down your classification possibilities by knowing whether or not a rock is magnetic. Also if you know the density of a rock you can use that information to help you classify the rock. To find the density of a rock you need to find the mass of the rock with a balance, and find the volume of the rock. You can find the volume by placing some water in a beaker and reading off how much water is in it, then place the rock in the beaker with the water and see how where the top of the water reads at then. Then you need to take the final volume minus the initial volume to find the volume of the rock.