orthoclase

Orthoclase is a common mineral in the feldspar family, primarily composed of potassium, aluminum, and silica. It forms in many types of rocks, especially granite and pegmatites. Recognizable by its light color—white, pink, or flesh-toned—it often appears as blocky or tabular crystals. Orthoclase is valued in jewelry when it has a transparent or translucent quality, called "moonstone" when it exhibits a soft glow. It plays a key role in the Earth's crust, contributing to the formation of rocks and giving insight into geological processes. Its physical properties include a hardness of 6 and characteristic cleavage, splitting easily along specific planes.