PETROGRAPHIC GEOLOGY AND DESCRIPTIONS. 503 



(iabliro. Noryto.] 



They are sometimes cleaved in two directions, and extinction is parallel to one of 

 these cleavages. Birefringence is low i. e., too low for a mica. The maximum of 

 pleochroism, which is extreme, is parallel to n s and with the direction of extinction. 

 A grain cut perpendicular (nearly) to an optic axis does not show a black cross in 

 convergent light, but the figure of a biaxial mineral. These characters exclude it 

 from the mica series, and especially from biotite. 



There are occasional clusters of Inotitc scales, strongly pleochroic. 



Two sections examined. 



Aye. (Jabotian. N. n. \v. 



No. 704. UABBKO. 



.M:iyhc\v hike, south from the little island crossed by the east and west town line. 

 Kef. Annual Report, x, page 82; Bulletin ii, page 89. 



Mi';/. A heavy, rusty, magnetited gabbro. 



Mir. The feldspar has extinction on 010 at 28" -indicating loln-ailorUc. It 

 followed the olivine in crystallization. 



The pyroxene is partly i/inl/ttyi' and partly any id'. Besides the characteristic 

 inclusions arranged in lines, it embraces many others that are scattered helter- 

 skelter, and which sometimes have orientation and polarization of their own. 



Ifoniinyifef ?) the green and yellowish decomposition product from the olivine, is 

 also seen in this rock, but not so often as rims between the magnetite and the 

 feldspar. 



liidfite, pi'.intiiK', nlicine, hroini, liornltli'iule, iiioyitetitc, make up the rest of this 

 rock, the last in great amount, and the second only as isolated scales in the altered 

 feldspar. The olivine is in large grains, frequently surrounding the magnetite. 



Two sections examined. 



Ayr. Cabotian. N. H. w. 



No. "On. NOKYTE. 



Appears like a metamorphic rock, bedded and dipping north about 45 at a point a little back (north) 

 from the shore, a short distance west from Mayhew's location, which underlies the iron-bearing rock, and the 

 iron ore, and has been styled changed quartzyte." Near the north shore of Mayhew lake and probably near the 

 west line of sec. 31, T. 65-2 W. 



Kef. Annual Report, x, pages 82, 83; Bulletin ii, page 94. 



Ma]. A rather fine-grained, gray, granitoid rock, composed of feldspar, pyroxene 

 and a little biotite. 



Mir. M. K. Wadsworth's description of this section is as follows:* 



" Its thin section under the microscope shows an irregular aggregation of short 



crystals, with rounded or irregular outlines, as seen in Nos. 777 and 698, which marks 



many rocks whose present structure is due in part or whole to the recrystallization 



of its constituents under the influence of water action. The pyroxenic constituents, 



Bulletin ii, p. 94. 



