XL] GRANITES AND GRANITIC VEIN-STONES. 215 



times two or three inches in diameter, scattered through the 

 feldspar. 



45. The veins hitherto noticed occur in gneiss, but on the 

 river Eouge one consisting of large masses of quartz and albite 

 is found in crystalline limestone. A remarkable vein described 

 by Sir William Logan in Blythefield, Ontario, traverses alter- 

 nate strata of limestone and gneiss, and has a breadth of not 

 less than 150 feet. It consists in great part of a coarsely 

 cleavable pale green pyroxene (sahlite), with a dark green 

 hornblende, phlogopite, and calcite. Portions of the vein-stone, 

 however, consist of an admixture of orthoclase, quartz, and 

 black tourmaline, showing the transition from the calcareous to 

 the feldspathic type of veins. In Ross, Ontario, a vein holds 

 large isolated crystals of white orthoclase imbedded with black 

 spinel, apatite, and fluorite in a base of lamellar pink carbonate 

 of lime. One of the most remarkable of these composite veins 

 is in Grenville, Quebec, and was formerly worked for graphite. 

 It cuts a crystalline limestone, itself holding graphite and 

 phlogopite, and has afforded not less than fourteen distinct 

 mineral species, namely, calcite, apatite, serpentine, wollastonite, 

 pyroxene, scapolite, orthoclase, oligoclase, garnet, idocrase, zircon, 

 quartz, sphene, and graphite. An adjacent vein abounds in phlo- 

 gopite, with pyroxene and zircon. A not less remarkable vein 

 is that described by Blake in Yernon, New Jersey (this Journal 

 (2), XIII. 116), in which calcite, fluorite, chondrodite, phlogo- 

 pite, margarite, spinel, corundum, zircon, sphene, rutile, menacca- 

 nite, pyrite, and graphite occur. Some of these contain bary- 

 tine, and in one case I have observed natrolite, both seemingly 

 filling cavities, and of later origin than the other minerals. 

 The remarkable zinciferous minerals, franklinite, zincite, dys- 

 luite, and willemite, found in the Laurentian limestones of 

 New Jersey, appear from the descriptions of H. D. Rogers to 

 belong to calcareous vein-stones. Granitic veins are found 

 traversing the magnetic iron ore-beds of the Laurentian series. 

 I have described one in Moriah, New York, which includes 

 angular fragments of the magnetite which forms its walls, and 

 consists of a cleavable greenish triclinic feldspar, with quartz 



