1870.] T. S. HUNT — ON GRANITIC ROCKS. 395 



that these, and indeed a great proportion of quartzo-feldspathic 

 veins are of aqueous origin, and have been deposited from solu- 

 tions in fissures of the strata, precisely like metalliferous lodes. 

 This remark appHes especially to those granitic veins which in- 

 clude minerals containing the rarer elements. Among these are 

 boron, phosphorus, fluorine, lithium, rubidiam, glucinum, zirco- 

 nium, caesium, tin and columbiura ; which characterize the mineral 

 species apatite, tourmaline, lepidolite, spodumcne, beryl, zircon, 

 allanite, cassiterite, columbite, and many others." — (^Geology of 

 Canada^ p. 476, also p. 644.) 



In this connection I referred to the occurrence of orthoclase with 

 quartz, calcite, zeolites, epidote and native copper in certain 

 mineral veins of Lake Superior, so well described by Prof. J. D. 

 Whitney. (American Journal of Science II, xxviii, 16). The 

 associations, according to him, show the contemporaneous crvstal- 

 lization of the copper, natrolite, calcite and feldspar, which last 

 was found by analysis to be a pure potash-orthoclase. 



§ 14, In 1864, this view was still farther insisted upon in the 

 Amer. Journal of Science (II, xxxvii, 252), where, in speaking 

 of mineral veinstones "^ which doubtless have been deposited 

 from aqueous solution," it is added, " while their peculiar arrange- 

 ment, with the predominance of quartz and non-silicated species, 

 generally serves to distinguish the contents of these veins from 

 those of injected plutonic rocks, there are not wanting cases in 

 which the predominance of feldspar and mica gives rise to aggre- 

 gates which have a certain resemblance to dykes of intrusive gran- 

 ite. From these, however, true veins are generally distinguished 

 by the presence of minerals containing boron, fluorine, phosphorus, 

 caesium, rubidium, lithium, glucinum, zirconium, tin, columbium, 

 etc. ; elements which are rare, or found only in minute quantities 

 iu the great mass of sediments, but are here accumulated by de- 

 position from waters, which have removed these elements from 

 the sedimentary rocks and deposited them subsequently in fissures." 



In the Report of the Geological Survey of Canada for 1865 (p. 

 192), I have, in describing the veins of the Laurentian rocks, in- 

 sisted still farther on the distinction just drawn between granitic 

 dykes and granitic veinstones, which latter I have proposed to 

 call endogenous rocks, to indicate the mode of their formation, 

 and to distinguish them from intrusive or exotic rocks, and sedi- 

 mentary or indigenous rocks. 



§ 15. The peculiar banded arrangement, which is so charac- 



