ZIRCON. 201 



Varieties and Composition. Transparent led specimens 

 are called hyacinth. A colorless variety from Ceylon, hav- 

 ing a smoky tinge, is called jargon ; it is sold for inferioi 

 diamonds, which it resembles, though much less hard. The 

 name zirconite is sometimes applied to crystals of gray 01 

 brownish tints. Consists of silica 33*2, zirconia 6o*8. In- 

 fusible before the blowpipe, but loses color. Forms with 

 borax a diaphanous glass. 



Dif. The hyacinth is readily distinguished from spinel 

 by its prismatic form and specific gravity, as well as its 

 adamantine luster and a less clear shade of red. Its infusi- 

 bility, hardness, and other characters, distinguish it from 

 tourmaline, idocrase, staurotide, and the minerals it re- 

 sembles. 



Obs. The zircon is confined to the crystalline rocks, in- 

 cluding lavas and granular limestone. Hyacinth occurs 

 mostly in grains, and comes from Ceylon, Auvergne, Bohe- 

 mia, and elsewhere in Europe. Siberia affords crystals as 

 large as walnuts. Splendid specimens come from Greenland. 



In the United States, fine crystals of zircon occur in Bun- 

 combe county, N. C. ; of a cinnamon red color in Moria, Es- 

 sex county, N. Y. ; also at Two ponds and elsewhere,, Orange 

 county, in crystals sometimes an inch and a half long ; in 

 Hammond, St. Lawrence county, and Johnsbury, Warren 

 county, N. Y. ; at Franklin, N. J. ; in Litchfield, Me. ; Mid- 

 dlebury, Vt. ; Haddam and Norwich, Conn. 



The name hyacinth is from the Greek huakinthos. But 

 it is doubtful whether it was applied by the ancients to stones 

 of the zircon species. 



Uses, The clear crystals (hyacinths) are of common use 

 in jewelry. When heated in a crucible with lime, they lose 

 /heir color, and resemble a pale straw-yellow diamond, for 

 which they are substituted. Zircon is also used in jewelling 

 watches. The hyacinth of commerce is to a great extent 

 cinnamon stone, a variety of garnet. 



The earth zirconia is also found in the rare minerals eudialyte and 

 tcOhlerite ; also in polymignile, aschynite, arstedite ; also sparingly in 

 ^ergusonite. 



What is the composition of zircon? What are its varieties? Hew 

 does it differ from spinel and other minerals? How does it occur 

 What is said of its uses ? Does the earth zirconia occur in other min 



erals ? 



