FIRST MINING EXPOSITION AT DENVER, COLORADO. 
83 
somé of the veins are said to be wide and continuous, and to yield mucii 
more tban our very interesting mines in Transylvania. The district, where 
the principal mines are situated, lies hetween Magnólia on the soutli, and 
Ballarat on the north, comprising a space of 1 3 miles in length and 3 miles 
in width. Somé telluric minerals have alsó been recently found in the San 
Juan district. 
The species Petzite and Sylvanite are of the most frequent occurence, 
while the Coloradoite is the most uncommon 
I had the opportunity of buying the following american telluric 
minerals: 
1. Natívc tellurium, found in several mines (Boulder County), on my 
specimen somé native Cfold is visible. The rock is a vein-quartzite, 
while the native Tellurium of Facebay (near Zalathna) occurs in 
the fissures and cavities of the Carpathian Sandstone accompained very 
often by small crystals of Pyrite in such a manner, that the center of the 
fissure is fiiled with native Tellurium in highly lamellar masses or in small 
tin white crystals coating the cavities of the Tellurium őre; while the gra¬ 
nulál - quartzite surrounding the Tellurium is impregnated with crystals of 
Pyrite of an anterior date of formation. The Facebay locality has nőt been 
worked fór many years, and the spare specimens of tliis are very expeu- 
sive; while the american species is easily accessible, and according to 
Genth a mass of 25 pounds was once found, in one of the mines. 
(John Gay). 
The metál lic Tellurium is very interesting as an object fór a syste- 
matical collection, bút is of no practical use. In America the Tellurium as 
the constituent element of the telluric ores is left to escape. In Hungary 
tolerablv great masses of it were previously extracted írom the compounds 
fór scientific purposes, bút the dernand fór it is so exiguous, that they were 
obliged. to give up its extraction. 
Lionite seems to be a peculiar kind of an impure Tellurium, quite 
peculiar to the Mount Lion mine, Colorado. 
2. Altaite in well formed crystals, the combination of octahedron 
and hexahedron. It is found in several mines (Cold Spring, Síidé, Bed 
Cloud etc.) in the Boulder Co. The rock is a vein-quartzite. The telluric 
lead is nőt known in Transylvania. 
3. Sylvanite , the gold and silver telluride is one of the most valuable 
ores. One specimen is a pseudomorph of gold after Silvanite. The. 
outlines of the original Sylvanite are still visible, bút the substance 
has undergone a Chemical change: the tellurium has been carried 
away and the Gold remained in a very porous state. The locality is 
Boulder Co, bút the mine is no longer worked. Another specimen was 
a roasted Sylvanite contained in a quartzite vein (Báron mine, Dolina, 
6 * 
