86 
DR. J. SZABÓ 
similar case in Hungay: only one of tlie traehytic groups of Trasylvania 
the Goid and Silver contains compounds of Tellurium, while in tlie other 
three groupes (Rézbánya, Börzsöny and Zsarnócza) the mineral-veins of 
the traehytic rocks contain only the Tetradymite. 
The Bismutlitelluride of Börzsöny (Deutsch-Pilsen), (6 miles north of 
Budapest) contains Silver, and therefore has been named Wehrlite by Dana 
after the Prof. of chemistry at the mining academy of Schemnitz, to wliom 
Science is indebted fór the first (rather imperfect) analysis of this very rare 
mineral. The same has been recently analysed by Sipöcz( 1880), (to whom I 
gave the pure matériái of the splendid sq>echnen of the University-Collec- 
tion) with the following result: Bi 59 - 47, Ag 4*37, Fe 029, Te 35*47, 
S —, = 99*b0. Sp. G. 8*47. This analysis shows considerably more Silver 
than the old one by Wehkle. 
As regards the rock formation, in which the veins bearing the Telluric 
compounds are to be found in Hungary, it is the Trachyte and especially 
the Biotite Quarztrachyte, therefore the older division of this rock-family 
or sometimes such of the surrounding rocks, in which the fissure containing 
the mineral-vein íinds its continuation. Such a rock is in most cases the 
Carpathian Sandstone. 
In Colorado as well as in Hungary the vein-rock is a grey Quartzite; 
bút all the otter matériái, which I have seen is so much altered, so mucii 
decomposed, that the attempt of deciphiring the mineralogical associa- 
tion cangive only a more or less approximate result. 
The rock specimen from the Inter Óceán mine (Boulder Co.) con¬ 
tains somé glassy quartz grains sometimes with hexagonal outlines, and a 
white felspar which is fór the greatest part friable, bút nőt always witliout 
a hard nucleus, which in the fiamé analysis invariably proved to be the 
potash felspar. A thin section seen through the microscope shows somé 
lew remains of mica with much altered substance, and somé rare grains 
x>f microcline. 
There was anotlier rock from the Síidé mine (Boulder Co.) very simi¬ 
lar to this, bearing Hessite; the felspar of which alsó gave the fiamé reac- 
tions of the potashfelspar. 
The surface rock of the Philadelphia mine is less decomposed, its 
felspar is a potashfelspar fusing with outer bubbles. The thin section 
shows somé very rare scales of brown mica. 
From the two c-haracters of the potashfelspar, namely it being fusible 
to a globule with bubbles on the surface, and exhibiting in polarized light 
the structure of the microline, I may infer, that the rock in question belong 
to the old series of gneissic and granitic formation, because those two cha- 
racters are in the newer eruptive rocks never met with. 
In the geological Atlas of Colorado (Hayden) the whole chain of the 
