PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 491 



Apotrachyte.] 



idiomorphic feldspathic remnants, whose orientations are the same, and the same as 

 that of the large crystal in which they lie. Even their forms are distinct and parallel 

 with those of the large enclosing crystal. The perimeter of the large crystal excluded 

 the reddened substance, and forms a continuous feldspathic band about as wide as 

 the enclosed remnants. It appears, therefore, that a porphyritic triclinic. crystal has 

 been almost wholly removed by the entrance of the reddened substance in the 

 manner of a micro-pegmatyte (or more properly in the manner of a micro-perthite), 

 the original crystal only remaining in the remnants. These remnants are frequently so 

 grouped and shaped that they are plainly outlined by the cleavages of the original 

 feldspar. Some of these feldspars are striated distinctly, and have a nearly parallel 

 extinction, indicating oligoclase, and others do not show any striation. 



Quartz is not abundant, indeed is rare, but is seen in a few isolated small grains. 

 And there is still less of magnetite and of chlorite. The rock is essentially coarsely 

 crystalline, but poorly differentiated, almost quartzless, one of the forms of the "red 

 rock" of the state. Small grains that seem to be augite (or diopside], more or less 

 chloritized, are grouped so as to appear to be originally parts of a larger crystal 

 which pierces the reddened substance idiomorphically. 



Aye. Cabotian. 



Remark. This rock appears to have been the result of a profound alteration of 

 some earlier rock (perhaps a basic one) by the entrance of the reddened element and 

 some quartz. If quartz had been more abundant in this invading element it is quite 

 probable that much micro-graphic structure would have resulted, and if iron had 

 been less abundant the reddened substance would have been some distinct secondary 

 feldspar and would have constituted, with the remnants of the original feldspar, a 

 micro-perthite. As a whole the rock is similar to the "intermediate rocks "'of 

 Bayley along the gabbro contact. N. H. w. 



No. 687. APOTRACHYTE. (Spherulitic.) 



Same locality as No. 686. 



Ref. Annual Report, x, page 78. 



Meg. A very fine-grained, reddish-brown rock, somewhat porous in texture and 

 earthy in appearance. 



Mic. A few highly altered porphyritic feldspars are seen in a reddish ground- 

 mass in which magnetite and hematite are abundant. The groundmass is considerably 

 reddened and consists of numerous circular areas which have a more or less distinct 

 radial structure. Typically each area is composed of (1) A central deeply reddened 

 mass, (2) A zone of lighter color, and (3) A zone like the centre. The radiating 

 structure passes through all three zones but is more marked in that of lighter color. 

 This radiating structure is'made by indistinct fibres with approximately parallel 



