OttDER vii. DODECAHEDBAL GASKET. 361 



the present state of Mineralogy we must therefore leave 

 them in that connexion with each other. The distinction 

 introduced among those species which have received parti- 

 cular names and denominations, does not correspond to 

 those properties, for it depends almost entirely upon acci- 

 dental circumstances. Of these species, Grossular occurs 

 only in imbedded crystals of the forms of icositetrahedrons, 

 and combinations of it with the dodecahedron. Its co- 

 lours are confined to asparagus-green and mountain-green. 

 Pyrcnette also occurs only in small imbedded crystals in 

 limestone; these are dodecahedrons, and generally greyish- 

 black, but sometimes so pale as to be greyish-white and 

 semi-transparent. Melanite possesses nearly the same 

 forms as Grossular, generally imbedded, and of a velvet- 

 black colour. Pi/rope occurs only in grains, and is remark- 

 ably distinct by its pure translucency and blood-red colour, 

 which is not found in any other variety, though they ap- 

 proach very near to it. Among the gems commonly con- 

 sidered by jewellers as Spinel, there are some which, in 

 colour, hardness, and specific gravity, agree much more with 

 Pyrope than with dodecahedral Corundum, and therefore 

 very likely belong to the same species. Among the va- 

 rieties called Garnet, we find every simple form and com- 

 bination noticed above among the crystalline varieties, also 

 grains and massive varieties ; it contains likewise every 

 shade of the series of colours, &c., and it is therefore only 

 in the particular union of several of these properties, that 

 we must look for the distinction of the above-mentioned 

 species. The colour of precious Garnet is always red, 

 its crystals are formed imbedded, it is the only variety 

 that occurs in grains, and if compound, it presents lamellar 

 composition. Common Garnet seldom occurs in red colours, 

 and these are of dirty tinges ; its crystals are generally im- 

 planted, and the composition granular, but not impalp- 

 able. Colophonite is a compound variety of yellowish- 

 brown and reddish-brown, or oil-green and honey-yellow 

 colours, consisting of roundish particles of composition, 



