Orthoclase is the transparent to opaque form of yellow potassium feldspar. This mineral is sometimes mistaken for citrine or yellow beryl and is primarily found in Madagascar.
The name orthoclase comes from the Greek for "break straight," because this variety of feldspar is frequently found with crystals joined at a 90 degree angle. Feldspars are one of the most widespread minerals in the world, making up nearly 60 percent of the Earth's crust. Other members of the feldspar family of minerals include moonstone, sunstone, amazonite and labradorite. Orthoclase is often colorless or champagne-colored. Champagne-colored orthoclase is frequently used in jewelry and looks best in natural daylight. Its luster is vitreous or pearly, and orthoclase gemstones that exhibit opalescence are generally referred to as moonstone. Its ranking of 6 on the Mohs hardness scale makes orthoclase suitable for jewelry in the shape of pendants, earrings and pins, as well as gem collections.
Orthoclase can be found in many composite minerals like granite, but these deposits are not considered gem quality. Australia, Burma (Myanmar), Madagascar, Sri Lanka, the United States and Zimbabwe have mining operations for gem-quality orthoclase. However, the best quality deposits are found in Madagascar, where we source orthoclase.