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LABRADORITE AND OTHER GEMS. 33 l
differs from the orthoclase adularia. Sunstone of very good
quality is known to occur in certain localities in the United States, but those of the finest quality are brought from Archangel, Russia. Adularia. — This mineral is a transparent variety of orthoclase, which is characterized by pearly or opalescent reflections,
and a play of- colors resembling labradorite ; it was named for one of the peaks of St. Gothard, where it is found, and is identical with the valencianite of Mexico. The opaque, green adularia is called amazon-stone — a term applied to varieties of other species; and it is sometimes used for jewelry, under the name of moonstone. Phenakite. — This name is equivalent to "deceiver," and
was conferred upon this species on account of its having been frequently mistaken for other minerals. The white variety may easily pass for the diamond if the play of prismatic colors is very conspicuous, as not unfrequently happens. It is sometimes transparent, but oftener translucent or clouded. The colors do not embrace a wide range, consisting of brown, and a bright wine-yellow inclining to red : its hardness is superior to that of quartz, and the crystals, often of large size, are doublerefracting. Silica and glucina are the only substances which enter into its composition. The best specimens come from the emerald and chrysoberyl
mines of Asiatic Russia, and some stones of suitable ^quality for jewelry have been discovered at Pike's Peak, Colorado. As a gem, phenakite is rare, but may be found in collections ; the British Museum contains some fine crystals. Zo7iochlorite. — This mineral species was discovered by Dr.
A. E. Foote, in 1868, at Neepigon Bay, on the north shore of Lake Superior, in an amygdaloid trap, associated with some other minerals. Its constituents are lime, silica, alumina, |
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