So you have a few rocks that you want to crush for an independent science project or just for your own enjoyment. There are many ways to crush rocks, including using a professional-grade industrial rock crusher or a rock tumbler for personal use. If you want to get started right away, though, and need to crush rocks with materials lying around your house, a hammer is an effective and simple way to achieve this.
Preparing the Rocks
Sift through the collection of rocks and remove any rocks that are too large (use your own judgment based on the size of hammer you are using) or too small to be successfully crushed.
Clean the final collection of rocks with water and a hard bristled brush. Be sure to remove any dirt, glass or loose fragments.
Find a hard, flat surface that you won't mind denting or dinging, and clear it of any items.
Roll out the thick cloth onto the cleared flat surface.
Set rocks on the thick cloth and wrap the cloth around the rocks. Bunch together the excess cloth, making a sack with the fabric, and tie off with an elastic band. This closes the cloth in order to prevent pieces or shards flying out once you begin crushing the rocks.
Hammering the Rocks
Turn the cloth around, with the rocks now securely placed inside, so that the elastic band is on the bottom, leaving you a flatter surface area to hit.
Ensure that your work gloves and safety goggles are on properly. If any piece of rock does come loose from the cloth, it could cause serious damage to your eyes or hands if you are not wearing the proper protective gear.
Use the hammer to strike the cloth. You should start to hear the rocks breaking inside the cloth if you are hitting with enough force.
Hammer the rocks until they are crushed as much as you want. Open the cloth after every few blows to check the status of the rocks to avoid over-crushing.
Once the rocks are crushed, use the hard-bristled brush to sweep the rock pieces into an empty container.