n. [ Gr. 'an priv. + 'orqo`s straight ('orqh` sc. gwni`a right angle); not in a right angle. ] A mineral of the feldspar family, commonly occurring in small glassy crystals, also a constituent of some igneous rocks. It is a lime feldspar. See Feldspar. [ 1913 Webster ]

n. [ Gr. 'orqo`s straight. ] (Min.) A variety of allanite occurring in slender prismatic crystals. [ 1913 Webster ]

n. [ So named after Volborth, who first discovered it. ] (Min.) A mineral occurring in small six-sided tabular crystals of a green or yellow color. It is a hydrous vanadate of copper and lime. [ 1913 Webster ]