MODE IV. FELSITE. 1(>9 



cipality of Fulda ; in the Rhongebirge ; at Hohen- 

 tinel and Hogau, in Upper Suabia ; at Vicenza, 

 in the Euganean mountains ; on the Pic de Teyde, 

 in Teneriffe; and in great abundance in South 

 America, as I suspect that much of the porphyry 

 of Humboldt will prove to be porphyry-slate." 



It may likewise be observed, from Brochant's 

 description, that patrinite sometimes occurs in glo- 

 bular masses, implanted in other rocks ; and also 

 sometimes assumes the prismatical form, in groups 

 of more or less regularity. 



To these remarks may be added the curious 

 description by Klaproth, which accompanies his 

 analysis. 



" The schistpse-porphyry is a species of stone, 

 which, notwithstanding that it so frequently occurs, 

 and even in masses forming entire mountains and 

 rocks, yet was doomed by a singular fate long to 

 continue to be disregarded, unknown, and con- 

 founded with other stones. 



"The first denomination, under which it has 

 been admitted in oryctognostic treatises, is that of 

 hornschiefer (horn-slate). However, this name 

 does not exclusively belong to it ; for which reason 

 various authors denote by the same name several 

 different species of stones. This German deno- 

 mination seems to have been occasioned by the 

 Latin corneus fssilis of Walkrlus ; though it is 



