Manufacture of fertilizer, green and blue pigments, host material for storage of nuclear waste, protective coatings on metals to prevent rust, occasionally used as a gemstone.
6 Orthoclase Feldspar
Raw material for the manufacture of some glasses, some ceramics (porcelain), constituent of scouring powder, gemstone (moonstone - an intergrowth of orthoclase and albite). Feldspar - 1st most abundant mineral in the Earth's continental crust.
Glass / window panes, eyeglasses, stained glass windows, cell phones (keeps the phone's clock and calendar accurate), provides base frequency for phone calls, gemstone (amethyst and citrine).
Jewelry (fragile gemstone).
Bonding agent in jewelry making, manufacture of sandpaper, as an abrasive, grinding wheels, ornamental uses, scratch-resistant optics, instrument windows for satellites and spacecraft.
Jewelry / gemstones, cutting and drilling applications, membranes used in lasers, x-ray machines and vacuum chambers (diamonds are resistant to heat).