
ORE-FORMATIONS 265 
to stray beyond the zone of altered and metamorphosed 
country-rock which surrounds it. They may occur in any 
kind of rock, and are frequently accompanied by the “contact 
minerals” referred to in a previous chapter (p. 217). Good 
examples are supplied by the cassiterite-veins which occur 
in genetic connection with batholiths of acid igneous rock, 
and the apatite-veins which are in like manner associated 
with masses of gabbro. The contents of these veins, as we 
have seen, appear to have been extracted from the still liquid 
or not yet fully congealed igneous masses and carried into the 
surrounding rocks. They are, in short, among the phenomena 
of contact metamorphism. According to Professor Vogt, 
SS 
cae 

FIG. 107.—SECTION. CONTACT ORE-FORMATION OF GOROBLAGODAT (URAL 
MOUNTAINS). (After T. Tschernyscheff.*) 
g-r, garnet-rock ; p, orthoclase-porphyry; 0, magnetic iron-ore. 
who has made such phenomena a special study, many other 
ore-formations met with in the vicinity of eruptive masses 
are of the same origin. As examples, he refers to the pyritic 
deposits occurring at Sulitelma and other places in Norway, 
at Tharsis, San Domingo and elsewhere in Spain, at Ram- 
melsberg in the Harz, and Schmdllnitz in Hungary. In all 
these cases the formation of the ore-deposits is ascribed to 
pneumatolytic processes, following eruptive intrusions. Vogt 
further draws attention to the fact that the younger gold and 
silver veins (such as those occurring along the Carpathians, 
and at many places in Colorado, Utah, Nevada, California, 
Mexico, Peru, Bolivia, New Zealand, Japan) are in like 
manner closely associated with recent eruptions of igneous 
* Until quite recently the iron-ore of Goroblagodat was considered 
to be an example of magmatic segregation, which is certainly suggested by 
Tschernyscheff’s section, It is now, however, believed to be of epigenetic 
origin, 

