870 PHYSIOGRAPHY. CLASS n. 



this error had been discovered, several mineralogists yet 

 continued to divide those varieties, and grounded the dif- 

 ferences upon forms of crystallisation, colour, &c. all of 

 which can be of no avail, if we rightly consider the species 

 in Mineralogy. Hyacinth possesses the brightest colours, 

 least inclining to grey, and such combinations, in which 

 the regular four-sided prism, in combination with the 

 fundamental pyramid, is in a diagonal position, as in Fig. 

 97-> either alone, or at least presents broader faces than 

 the other prism, in parallel position with P, and which 

 replaces the lateral edges of the pyramid, and of the 

 other prism. Both, crystals and grains of Hyacinth 

 are smooth and shining, those of Zircon are frequently 

 rough. Zircon besides possesses tints of colour, that in- 

 cline much more to grey. The differences in cleavage, 

 supposed to take place between the two varieties, do 

 not exist, at least they are not greater than we are ac- 

 customed to find them in other species. Hence it is evi- 

 dent that all the varieties must be necessarily included 

 within one and the same species, which then appears as 

 one of the most remarkable in the whole mineral kingdom. 



2. Zircon and Hyacinth consist, according to KLAP- 



ROTH, Of 



Zirconia 69-00 70-00. 



Silica 26-50 25-00. 



Oxide of Iron 0-50 5-00. 



Before the blowpipe it loses its colour, but does not melt. 



3. The varieties of this species have always been found 

 in imbedded crystals in mountain masses, or in beds includ- 

 ed in them. They seldom form small masses, consisting 

 of several crystals. From these repositories it is washed 

 into the sand of rivers, where it is notunfrequently met with. 



4. In the Saualpe in Carinthia, pyramidal Zircon occurs 

 in a bed of Albite and of prismatoidal Augite-spar, called 

 Zoisite, in gneiss ; the varieties from New Jersey and other 

 localities in North America, from Greenland, from Ceylon, 

 &c. occur likewise in gneiss or in talcose rocks ; those from 

 Frederiksvarn in Norway, in zircon-syenite. Near Puy 



