260 DESCRIPTIONS OF MINERALS. 



Composition. Zr 4 Si = Silica 33, zirconia 67=100. B.B. 

 infusible, but loses color. 



Varieties. Transparent reel specimens are called hya- 

 cinth. A colorless variety from Ceylon, having a smoky 

 tinge, is called jargon; it is sold for inferior diamonds, 

 which it resembles" though much less hard. The name 

 zirconite is sometimes applied to crystals of gray or brown- 

 ish tints. 



Diff. Zircon is readily distinguished from species which 

 it resembles in other properties by its square prismatic 

 form, specific gravity, and adamantine lustre. 



Obs. The zircon is confined to crystalline rocks, occurring 

 in granite, gneiss, granular limestone, and some igneous 

 rocks. Zircon-syenyte is a syenyte with disseminated zircons. 

 Zircon often occurs in auriferous sands. Hyacinth occurs 

 mosth in grains in such sands, and comes from Ceylon, 

 Auvergne, Bohemia, 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, X. C. ; of a cinnamon-red color in Moriah, 

 Essex 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, X. J. ; in Litchfield, 

 Me. ; Middlebury, Yt. ; in Canada, at Grenville, etc. 



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. 



The clear crystals (hyacinths) are of common use in 

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

 their color, and resemble a pale straw r -yellow diamond, for 

 which they are substituted. Zircon is also used in jeweling 

 watches. The hyacinth of commerce is to a great extent 

 cinnamon stone, a variety of garnet. The earth zirconia 

 is used as an advantageous substitute for lime in the oxyhy- 

 drogen lantern. 



Auerbacliite, Malacon, Tacky aphaltite, (Erstedite, Bragite, are 

 names of zircon-like minerals supposed to be zircon partly altered. 



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

 wohlerite; also in polymignite, ceschynite; also sparingly in fergu- 

 sonite. 



