SALMON — ON THE FOUJIATION OF OliE-VEINfl. 
389 
GENERAL CONSIDERATIONS ON THE FORMATION 
OF ORE-VEINS. 
(Translatoxl from the German of Professor Bernhard Cotta, of 
Freiberg, iiu'fh an Introcludorij Notice on tlic Study of Mineral 
Veins and Aletalliferous Deposits, hij H. C. Salmon, Esq., Plymouth.) 
(Contimied fronts i)ci{/e 368). 
These veins penetrate tlie crystalline schists, particularly the 
gneiss, in those localities where the latter are largely penetrated by 
porphyry. They also generally penetrate the porphyry ; only a few 
exceptions from this rule ser\'ing to show that the porphyry- 
eruptions continued into tlie period of the formation of the ore- veins. 
These veins form three or four principal groups, according to their 
direction,* which groups in general differ both in age and in con- 
tents. Still, all veins by no means show similar directions in 
connection with similar contents, or the converse, only these pre- 
dominant characteristics often coincide. Veins of distinctive con- 
tents are almost as much confined to certain localities as they are 
characteristic of definite directions. According to the contents we can 
distinguish tlu'ee or four paragenetic combinations of different ages, 
but which often extend into one another in such a manner that one 
fissure sometimes contains the products of two or three of these dif- 
ferent periods. These paragenetic combinations of vein-contents are : 
1. Principally quartz and hornstone, with frequent fragments of 
the neighbouring rock. There are also found, partly interwoven 
with the quartz, and partly in numerous drusy cavities. Brown-spar, 
Manganese-spar, Calc-spar, Strontian, Fluor-spar, Rothgiltigerz, 
Weisserz, Glaserz, native Silver, common Arsenical pyintes, Argenti- 
ferous pyrites. Blende, Weissgiltigerfedererz, Iron-pyrites, &c.t 
This so-called " great Quartz-formation" predominates in the fissures 
in the neighbourhood of Braunsdorf and Siebenlehn. We find about 
one hundred and fifty veins belonging to this combination. 
* Compare V. Bciist's Gangkarte. 
t I liave not cotisidered it advisable to give the strict mineralogical names to 
the mineral-species eiiumei-ated. The characteristic German ores I have given 
in the original names. 
VOL. 11. K IC 
