elæolite-syenite

Century Dictionary and Cyclopedia

1. n. A rock composed essentially of the minerals elæolite and orthoclase, and having a granitoid structure. With these minerals are very commonly associated others in lesser quantity, such as plagioclase, augite, hornblende, biotite, magnetite, apatite, zircon, sodalite, and sphene. The most important and classic occurrence of elæolite-syenite is in southern Norway, where it is the repository of many interesting minerals and of several of the very rare metals, such as yttrium, cerium, niobium, etc. Varieties of this rock containing considerable zircon have been frequently designated as zircon-syenite; a variety from Miask, Russia, with much mica, is known as miascite; one from Mount Foya in Portugal, which was supposed to contain hornblende, as foyaite; and one from Ditro in Transylvania, containing sodalite and spinel, as ditroite.