Turquoise is found in only a few places on earth,
dry and barren regions where acidic copper-rich ground water
seeps downward and reacts with minerals that contain phosphorus
and aluminum. The results of this sedimentary process is a porous
semi-translucent to opaque compound of hydrated
copper and aluminum phosphate.
Turquoise is a prime example of an opaque colored stone
that can me marketed both as a gem for jewelry and as an ornamental material.