

XL] GRANITES AND GRANITIC VEIN-STONES. 217 



which were at that time referred by the Geological Survey 

 of Canada to the Laurentian, but have since been found to 

 belong to younger series. Such are the veins containing argen- 

 tiferous fahlerz with mispickel, and that holding native gold 

 with a quasi-anthracitic form of carbon, both from Madoc, and 

 also the vein already noticed as occurring in the township of 

 Lake ( 36), which contains in one part bismuthine with tour- 

 maline, quartz, and graphite, and in another part calcite with 

 phlogopite. This latter vein occurs in an impure limestone, 

 associated with quartzite and micaceous schists, and belonging 

 to a series unconformably overlying the Laurentian, and re- 

 sembling the rocks of the White Mountain series. It will be 

 noticed that this vein is lithologically similar to those of the 

 Laurentian, which are not improbably of the same age. Cal- 

 careous vein-stones like those already described are not un- 

 known in the White Mountain rocks in Maine, where are 

 found, on a small scale, aggregates of crystallized pyroxene, 

 idocrase, and sphene, and others of calcite with hornblende, 

 apatite, and graphite ( 18), closely resembling the Laurentian 

 vein-stones of New York and Canada.* 



49. The various minerals of these calcareous vein-stones are 



[* In a note in the American Journal of Science for October, 1873, on The 

 Copper Deposits of the Blue Ridge, I have described the occurrence in Vir- 

 ginia, North Carolina, and Tennessee of great concretionary veins in gneisses 

 and mica-schists which I refer to the White Mountain series. These veins 

 are sometimes transverse to the stratification, and at other times inter- 

 bedded. An example of the latter is seen at the Ducktown copper-mine in 

 Polk County, Tennessee, where there is a banded arrangement of the large 

 masses parallel to the walls. The chief part of this vein is filled with pyrite, 

 pyrrhotine, and chalcopyrite, rarely with galena, blende, mispickel, and 

 molybdenite. These massive ores enclose large garnets, and are penetrated 

 with prisms of zoisite, hornblende, and pyroxene, sometimes several inches in 

 length. The hornblende crystals are bent and sometimes partially broken 

 across, the transverse fissures being filled with sulphurets, which are also 

 found between the cleavage planes of large pyroxene crystals. Other portions 

 of the vein are of vitreous quartz, holding metallic sulphides and rarely gar- 

 nets, while large masses of white cleavable pyroxene, and others of finely 

 fibrous greenish or white hornblende, occur, besides masses of white cleava- 

 ble calcite enclosing long prisms of green hornblende. This vein, with 

 the exception of the abundance of metallic sulphurets, resembles closely in 

 its contents the calcareous veins of the Laurentian rocks above described.] 

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