The Heber R. Bishop collection of jade and other hard stones

JADE is a name popularly given to several distinct kinds of ornamental stones of tough compact texture and of color varying from nearly white to a very dark green, which have been used from the earliest times in worked forms as weapons, utensils, ornaments and decorative objects Scientifically, however, the term is restricted to the two minerals Jadeite and Nephrite, and to Chloromelanite, a variety of jadeite rich in iron, of dark color and high specific gravity, These are chemically quite distinct substances, but notwithstanding this fact they are strikingly alike in many of their properties.Both are hard and compact, and usually of dis-_ tinctly fibrous texture, owing to which they are exceedingly _ tough, and may be carved into very delicate forms.Both are more or less translucent in most of their varieties, and are of various colors, although shades of green are most characteristic for both.In thin sections all varieties of both minerals appear nearly or entirely colorless and quite transparent.Both are 'susceptible of taking a high polish, and the polished surfaces frequently exhibit a very characteristic sheen.But in addition to the many characters shared by both minerals, each has propetties peculiar to itself which may be briefly stated.Jadeite is a silicate of aluminum and sodium.It almost always contains in addition small quantities of iron, calcium, and magnesium; in the variety called Chloromelanite the iron amounts to as much as ten per cent.Its chemical composition and crystalline character make it a member of the pyroxene group of minerals.It occurs rarely in distinct crystals, its usual form being a massive crystalline aggregate of closely felted fibres or granules.Its hardness is about 7, or that of quartz.Its specific gravity is close to 3.33.It fuses readily before the blowpipe to a clear glass, and is not decomposed by hydrochloric acid until after having been fused.'The color is VAS \ 4 METROPOLITAN MUSEUM OF ART.highly diversified, exhibiting an almost indefinite variety of shades and tints.'The commoner colors are, however, tones of -METROPOLITAN MUSEUM OF ART. BURMA.This is the country par excellence of jadeite, and is the only known locality where the mineral is found in situ.I. SMALL FracMEeNt from mines of Tammaw, Upper Burma.Collected by Dr. Fritz Noettling in 1892, and presented to the Collection by Dr. Max Bauer.2.