In the Proterozoic Era, about 3 to 500,000,000 years ago, slates were layers of black mud on the bottom of shallow seas. As epochs passed, the mud hardened by the process of compaction and cementation. At the same time the sea basins sank, allowing vast amount of new sediments to settle upon the hardening mud. After some 2 to 400,000,000 years the slates-to-be were firm shales that lay beneath younger formations 5 to 6 miles thick.

As the Paleozoic Era came to an end, the continents were squeezed by rocks beneath the oceans. They pushed the hardened sea muds upwards, shoving and crumpling them into huge, high folds.

When the shales were squeezed into sharp folds, pressure became so great that they raised nearly 6 miles of rock above them crumpling the top most shale into mountains. The intense heat and pressure generated caused many particles to recrystallize and flatten, often at right angles to direction of compression. This gave the rock a "grain" called slate cleavage that allows it to be split easily along one plane but not another.

Slate is chiefly comprised of quartz and illite, with mica, calcite, and minor quantities of other various minerals. Slates vary in color, most commonly seen in black, gray, red, purple, or green. Red color is due to the presence of Hematite, while green colors are due to Chlorite. Grey and black are due to carbon and/or graphite. Shades of red (purple) and tan are related to varying amount of iron oxides.

The natural beauty of slate enhances the quality, image, value and safety for residential and commercial projects and is an excellent product for both indoor/outdoor living styles.

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