Itrongay, Betroka, Finanrantosa, Madagascar Faceted by John Sinkankas The name Orthoclase is from the Greek for "straight fracture," because its two cleavage planes are at right angles to each other. Orthoclase belongs to the feldspar family of minerals that make up more than half of the Earth's crust. Very rarely these common minerals form crystals that are gem quality. Orthoclase can be found as a transparent colorless, champagne, or yellow gem resembling citrine quartz or yellow beryl. The present example is a cushion-cut lemon-yellow orthoclase, having excellent luster and clarity, RHC4307. Weighing approximately 11.65 carats and measuring 13.88 x 14.45 x 10.04 mm