The feldspar group is a fairly large group with nearly 20 members recognized, but only nine are well known and common. Those few, however, make up the greatest percentage of minerals found in the Earth's crust.
The following are some of the more common feldspar minerals:
The K-feldspars or alkali felspars:
- Microcline, (Potassium aluminum silicate)
- Sanidine, (Potassium sodium aluminum silicate)