114 C. H. GORDON — SYENITE-GNEISS (lEOPARD IIOCK) FROM CANADA. 



zones there is an abundance of fresh, finely and sharply striated feldspar 

 usually carrying nodular quartz inclusions. 



The quartz occurs distributed through the fine mosaic, often in lines 

 and stringers of elongated grains, in which, in addition to fluid inclusions, 

 the inclusions found in the microcline are abundant. 



Epidote appears in particles distributed through the microcline, while 

 the titanite often occurs in association with an opaque iron ore, probably 

 ilmenite. 



ELLIPSOIDAL SYENITE-GNEISS OR LEOPARD ROCK. 



The collection embraces specimens showing a gradation from forms in 

 which the constituents are rather coarsely crystallized and the feldspathic 

 cores approximately ellipsoidal through others in which they become 

 more and more elongated, flattened and distorted, accompanied by a de- 

 crease in the size of the grains, to those finally in which the constituents 

 are fine grained and arranged in parallel bands. The specimens were 

 taken from the dumps, which offered excellent opportunities for securing 

 an abundance of fresh material. 



Specimen 137 (141, 142, 143), which was taken from the block furnish- 

 ing specimens 131, 135, 136, represents the ellipsoidal rock in contact with 

 a mass of apatite, the ellipsoids sometimes thrusting themselves in be- 

 tween adjoining masses of apatite which may have belonged originally to 

 the same deposit. 



The interior of the feldspatliic lumps is sometimes coarse grained and 

 identical with portions of number 13G. They also show a small amount 

 of augite intergrown with the feldspar in these coarse grained parts, while 

 the finer grained, outer peripheral portions show little, if any, augite. 



Quartz is present in considerable amount in lines parallel with the 

 longer axis of the lump. In thin section cut transverse to the pyroxene 

 bands tlic}^ are seen to consist of a fine grained mosaic of feldspar, quartz 

 and augite, while the ellipsoidsare comi)osed chiefly of microcline in much 

 larger grains. In some cases, however, the ellipsoid is more or less fine 

 grained throughout and has lines of quartz extending through it parallel 

 with the longer axis of the lump. The augitic bands correspond in struc- 

 ture witli the granular f)elts observed in the coarse sj^enite. The constit- 

 uents all show a pronounced tendenc}'' toward a laminated arrangement. 

 They consist of microcline and plagioclase in about equal proportions, 

 mostly in small equidimensional grains. Quartz is quite abundant, 

 mostly in elongated grains and aggregates arranged in lines parallel with 

 the lines of augite. They contain as inclusions small i)lates of biotite 

 and occasionally small rounded grains of augite, unstriped feldspar, and 

 small rhombic sections of titanite. 



