Feldspar or Potassium Feldspar

Feldspar is the name of a large group of rock-forming silicate minerals that make up over 50% of Earth's crust. They are found in igneous, metamorphic, and sedimentary rocks in all parts of the world. Feldspar minerals have very similar structures, chemical compositions, and physical properties. Common feldspars include orthoclase (KAlSi₃O₈), albite (NaAlSi₃O₈), and anorthite (CaAl₂Si₂O₈).

To appreciate the importance of feldspar as a rock-forming mineral, let's consider its abundance in Earth's crust. Most of Earth's continental crust is made up of igneous rocks such as granite, diorite, and granodiorite. Feldspars are also important constituents of gabbro and basalt, which are the primary types of rock in Earth's oceanic crust. The accompanying chart shows how these rocks are made up mostly of feldspar minerals. As these igneous rocks are weathered and metamorphosed, their feldspar minerals become components of sediments, sedimentary rocks, and metamorphic rocks.

Feldspar in rocks: This chart summarizes the mineral compositions of common igneous rocks. It clearly shows that feldspar minerals are important constituents of granite, diorite and gabbro - these rock types make up the majority of Earth's crust.

Feldspar minerals have many uses in industry. They are used to manufacture a wide variety of glass and ceramic products. They are also widely used as fillers in paints, plastics and rubber. Several popular gemstones are feldspar minerals. These include moonstone, sunstone, labradorite, amazonite and spectrolite.

Crushed and powdered feldspar are important raw materials for the manufacture of plate glass, container glass, ceramic products, paints, plastics and many other products. Varieties of orthoclase, labradorite, oligoclase, microcline and other feldspar minerals have been cut and used as faceted and cabochon gems.