MEGASCOPICAL CHARACTERS. 107 



pyroxene and feldspar for a space of 10 centimeters from the apatite, 

 beyond which it is coarser grained and without the streaks of augite. In 

 this part the pyroxene is much diminished in amount and occurs only in 

 small, scattering aggregates and grains. Immediately next to the apatite 

 is a laj^er of feldspar, from 2^ to 1 centimeter thick, and much coarser 

 in grain than the succeeding bands. Moreover, the apatite mass is inter- 

 sected by several thin veins of feldspar and quartz, continuous with that 

 of the surrounding layer. These seams vary in width from 2 millimeters 

 to 5 millimeters, and vary proportionally in the size of grain. At one 

 point a grain of feldspar occupies the fall width of the seam. The 

 apatite is granulated on the outer surface of the mass, while the remain- 

 ing portion is irregularly fissured and broken, though not completely 

 crushed. 



In number 155 the layers are sharply plicated, and the augite and feld- 

 spathic constituents intermingle to a greater extent than in those with 

 straight layers, thus partially obscuring the banding. 



Microscopical Description. 



coarse syenite-gneiss. 



Specimen number 127 (129) consists of coarsely crystallized microcline 

 and a monoclinic pyroxene, with quartz, titanite, apatite and pyrite as 

 accessory constituents. Occasionally a small prism of tourmaline is ob- 

 served. 



The microcline is of a dark gray color and occurs in large grains inclos- 

 ing numerous well formed prisms of augite, usually long and slender. 



The rock is intersected in various directions by granular bands which 

 separate the mass into angular lumps of various sizes. These intersti- 

 tial bands are usually thin, but become somewhat thicker in places, and 

 consist chiefly of finely granular feldspar, quartz and augite. The quartz 

 appears usually in connection with these granular bands, sometimes in 

 aggregates of considerable size. These interstitial seams, therefore, con- 

 stitute a rather obscure network of fine grained feldspar, pyroxene and 

 quartz, inclosing various masses of coarse microcline and augite. The 

 augite in the quartz areas occurs both as grains and prisms. The latter, 

 however, are usually shorter than those inclosed in the microcline, and 

 present less well defined crystallographic outlines. Sometimes two short 

 prisms of the same size may be seen lying end to end, but not quite in 

 the same straight line. The idiomorphic individuals are elongated in 

 the direction of the vertical axis, and show a very nearly equal develop- 

 ment of the faces 00 P o5 (100), oo P o) (010), P (110). 



Section 129, cut transverse to the granular band seen in the hand speci- 



