That sounds like the name of a Do-Wop band. So since I touched on igneous rocks in general and granite in particular yesterday, today I want to talk about the metamorphics. The blue section in this diagram shows how metamorphic rocks end up back on the surface of the earth after their time spent below ground. That blue section is how we get three common metamorphic rocks used in homes: marble, quartzite, soapstone and a fourth, mysterious stone called serpentinite.

The term granite, as it's used commercially, is a bit of a generic term. Now I'm not a geologist but I do have an understanding of the fundamental geology that goes into the dimensional stone that ends up in peoples' homes. Granite's generally accepted to be an igneous rock composed primarily of silica that's formed in the mantle of the earth as magma gets squeezed between cracks in the earth's crust. As a liquid at that point, the magma tries to rise to the surface. It cools very slowly and under very high pressure then forms what are called batholiths --essentially huge domes that lie below the surface of the earth.

Rocks are divided into three categories: sedimentary, metamorphic and igneous. A lot of times these three classes are referred to as phases because each class can morph into each of the other classes over long periods of time. But that's can morph, it isn't automatic.

In English, those three classes can be pretty broadly defined like this: sedimentary rocks are formed by compacted sediment, metamorphic rocks are rocks that are transformed by heat and pressure after they're already formed and igneous rocks are formed by cooling magma. Some examples of sedimentary rocks are limestone and travertine. Some metamorphic rocks are marble, quartzite, soapstone and slate. Finally an igneous rock that's in a lot of peoples' homes is granite.