Apophyllite is a semi-precious gemstone and a class of minerals that are potassium-calcium fluoride-silicates with a high water content. The name comes from the Greek word apophyllízo, which means "it flakes off", because the minerals in this class tend to break apart when heated due to water loss.
The apophyllite sits on a bed of stilbite, which gets its name from the Greek stilbein = to shine, because of its pearly luster.
