Tanning+Granite

=Miami Tanning Salon=

The facing stone is a beautiful, polished, coarse grained granite.

Both the steps at the Post Office and the columns in the Justice building contain a lot of a mineral called feldspar. It is the most common mineral in the Earth's crust. However, at one of these locations the feldspar contains a lot of potassium, which colours it pink, and at the other location the feldspar contains a lot of calcium or sodium. This colours it grey-white.
 * EXERCISE**:

Is this rock rich in potassium or calcium/sodium?

An interesting point: Potassium is very weakly radioactive. Not enough to fry your brain, make your hair fall out, or make you sprout a second head, but it is detectable. There is no hazard in using it as a building stone as the type of radioactive particle doesn't really leave the rock.

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