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How to Split Slate

Kevin Mclain

Slate is a fine grain rock often used for decorative floors, fireplaces, driveways, roofs and walkways. This natural stone is actually made up of layers of hardened mud. Over time, any mud that has a mixture of clay minerals, quartz, chlorite and mica hardens to form slate.

The texture of the slate is rough and edgy and is gently split with a chisel, then cut with a wet saw, to keep it from busting into a bunch of little pieces. Splitting slate enables the person to design the piece of slate according to their decorative needs and sizes.

  1. Gather together the slate rocks that you plan to split. The slate rocks are chiseled into slate pieces big enough to fit into the wet saw. Place one of the slate rocks on a flat surface and completely saturate it with water. This prevents it from splitting when the rock is being chiseled.

  2. Mark the desired measurement across the top flat side of the slate rock with a measuring tape and a piece of chalk. The purpose of the measuring mark is to act as a guide while you chisel it in a straight line, until the rock separates into two separate pieces.

  3. Put the safety glasses on. Position the tip of a chisel over the end of one of the measurement marks. Tap the top of the chisel with a hammer so that the chisel makes an indentation into the rock.

  4. Tap the chisel with the hammer in 1 inch increments across the measurement mark. Create a pilot break in the slate rock. Move the chisel back to the starting point on the measurement and continue to chisel the slate rock until it splits into two separate pieces.

  5. Tip

    The water source that is attached to the wet saw keeps the slate from splitting while it is being cut by the diamond bit. The water also keeps the diamond bit cool to prevent it from getting too hot and burning up. Some slate saws require that an outside water source is attached to the saw while some model slate saws have their own water supply reservoir. Always use the chisel and hammer to first split the slate rock and then use the wet saw to fine cut the slate for the desired use.


    Always wear safety glasses to prevent any debris from the slate from getting into your eyes.