Feldspar is the most abundant mineral in rocks that are located at or near the earth's surface. Feldspar can have glassy white, blue, green, or red crystals. All feldspars contain silica and aluminum. When feldspars are exposed to the atmosphere they break down or weather easily. When they are broken down, feldspar forms other minerals, many of which are clay minerals. Feldspars also contain potassium which is a major nutrient for plant growth. The clays formed by weathered feldspar are used by pottery manufacturing plants. Kaolinite is the highest quality of the feldspar clays used by potters. Feldspar is number 6 on the Mohs hardness scale. Plagioclase is a form of feldspar that has a chemical make up of NaAlSi3O8. Plagioclase is usually white but can also be grey and greenish white. This mineral was abundant in the Moon rock samples.

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