260 DESCRIPTIONS OF MINERALS. 
Composition. Zr O,Si=Silica 33, zirconia 67=100. BB. 
infusible, but loses color. 
VARIETIES. ‘l'ransparent red 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 isasyenyte with disseminated zircons. 
Zircon often occurs in auriferous sands. Hyacinth occurs 
mostl\ in grains in such sands, and comes from Ceylon, 
Auvergne, Bohemia, and elsewhere in Hurope. Siberia 
affords crystals as large as walnuts. Splendid specimens 
come from Greenland. 
In the United States, fine crystals of zircon oceur in Bun- 
combe County, N. C. ; of a cinnamon-red color in Moriah, 
Essex County, N. Y.; also at 'wo 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. ; im lhitehftield 
Me. ; Middlebury, Vt.; in Canada, at Grenville, ete. 
The name hyacinth is from the Greek huakinthos. But 
it 1s 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-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. 
Auerbachite, Malacon, Tachyaphaltite, Cirstedite, Bragite, are 
names of zircon-like minerals supposed to be zircon partly altered. 
The earth zirconia is aiso found in the rare minerals eudialyte and 
wohlerite ; also in polymignite, aschynite; also sparingly in fergu- 
sonite. 

