102 C. H. GORDON — SYENITE-GNEISS (lEOPARD ROCK) FROM CANADA. 



side with the coarse grained variety (C), while on the other (B) there is 

 an excellent development of the ellipsoidal structure, with the longer 

 axes of the ellipsoids arranged approximatel}'' parallel to the adjacent 

 boundaries of the pyroxenite. The latter at the point marked A shows 

 an interlamination with apatite such as has been frequently noted in the 

 ai)atite regions.* 



The surface exposure shows one branch (D-F) of the syenite intrusion 

 narrowed and curving. At D the ellipsoids have become so flattened 

 and attenuated that in transverse section the}^ appear as parallel bands 

 of reddish white feldspar alternating with thin stripes of augite. At F^ 

 however, the ellipsoidal structure again appears with shar[) little trenches 

 surrounding the feldspathic ellipsoids, due to the weathering of the inter- 

 stitial augite layers (number 139). At E a branch is given ofl', which 



Figure 4. — Dike 0/ coarse Syenite-gneiss cutting Pyroxenite and inclosing Portions {A) of the 



latter. 



consists of the coarse grained syenite rock, with no indication of ellip- 

 soidal or banded structure. Other portions of the syenite rock make 

 their appearance at the surface here and there as lenses (G) in the 

 pyroxenite. 



On the brow of the hill above pit number 11 the pyroxenite is cut by 

 a dike of syenite, a foot or more wide, extending from north 10° west to 

 south 10° east. 



The dike dips into the hill at a slight angle with the vertical, and at 

 one point gives off a branch (C), which soon wx^dges out in the j)3a'ox- 

 enite. Fragments of the pyroxenite are inclosed in the syenite, as shown 



* W. Boyd Dawkins: Proc. Manchester Geol. Soc, 1884. 



Note.— The rocks referred to here are represented in the collection by the following numbers 



A = numbers 109, 110, pyroxenite. i)= number 139, ellipsoidal gneiss, weathered. 



£ = number 138, ellipsoidal syenite-gneiss. -E= *' 140, streaked syenite-gneiss. 



C= " 133, coarse syenite-gneiss. 



