Slate sandstone comes in various shapes since it is quarried from the mountains. It generally breaks away in 1- to 2-inch layers that are slightly rounded but mostly jagged around the edges. You can cut this sandstone into squares to resemble tile using a circular saw and masonry diamond blade. The average do-it-yourself homeowner can complete this project in 2 to 4 hours, depending on the size and scope of the project. 

Firstly, install the diamond blade onto the circular saw for use. The blade must be placed onto the saw with the arrow facing the direction of rotation of the circular saw drive shaft. Otherwise, the blade will not cut and may be damaged by the improper fit.

Secondly, place one straight line along one edge of the slate sandstone. Use the framing square placing it on one long edge of the slate and make a crayon mark using the construction crayon. These crayons can be purchased at any hardware store. If you intend to make 12-inch squares, make sure your line is at least 12 inches long.

Thirdly, measure along the line and place two marks on each end of that line 12 inches apart. Place the right angle of the framing square at one of these marks and draw a line perpendicular for 12 inches. Continue drawing right angles until you have a complete square.

Fourthly, wet the slate to prevent dust. Wear a dust mask when cutting into the slate, as well. Slowly cut the slate with the circular saw, following the square marks. Do not force the saw into the slate, but cut slowly and steadily until your square has been formed. Once the square has been cut out, use the saw to cut away any high ridges that may remain on the flat surface of the tile. Sometimes these rocks are not completely flat, so this method will serve at a grinder to smooth the flat surfaces of the stone, as well.