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How to Cut Slate Rock

Slate is a fine-grained metamorphic rock. Typically, slate forms from a parent rock of either mudstone or shale that is rich in clay minerals, quartz, chlorite, and mica. Many accessory minerals are also present in slate and often dictate the color of the stone. Slate forms from a low grade of metamorphism, which means that the application of low temperatures and pressures to the shale or mudstone formed the slate. During metamorphism, the slate develops cleavage planes along which the rock can easily break in one direction.

Things You'll Need

Slate rock slab
Chisel
Hammer
Wet circular saw with diamond blade
Dust mask
Measuring tape
Chalk

Instructions

- 1
  Split the slate rock into the desired slab thickness using a hammer and chisel. Slate will naturally and easily break along cleavage planes that form during metamorphism. Continue splitting the rock until you reach the desired thickness for a slab. If the rock does not split easily, you are likely perpendicular to the cleavage plane rather than parallel, so rotate the rock and try again. Wear appropriate safety equipment while breaking and cutting the rock such as safety goggles and dust mask.
- 2
  Place the rock slab on a flat cutting surface such as a saw stand or table. If your saw has a guide, place the slate rock against the guide to achieve a straight cut.
- 3
  Measure the length and width of the rock slab. Mark the rock with chalk lines where you want to cut the rock. Align the chalk marks with the blade on the saw.
- 4
  Cut the slab into the desired length using a wet circular saw equipped with a diamond blade. Dry saws can also cut slate; however, wet saws are preferred due to the decrease in dust production. Gently and slowly push the rock slab into the saw blade. Although slate is very durable, it cuts very easily.
- 5
  Repeat the cutting process to achieve the desired width for the slate rock slab.

Rocks & Minerals