Petrographical Relations of Laurentian Limestones. 19 



distinct outline, more or less polygonal, giving to a section 

 a defined mosaic or paving-stone appearance, characteristic 

 of a recrystallized metamorphic rock ; the structure is 

 granulitic. 



The presence of epidote, and particularly of scapolite 

 in this rock is of special significance, since these minerals 

 are frequent, and may almost be said to be characteristic 

 accompaniments of certain pyroxenites and amphibolites 

 which, in matamorphosed contact-zones, are the equiva- 

 lents of granular limestones. 1 The abundance of augite, 

 and its preponderance over the hornblende, than which 

 it is generally a mineral richer in lime, are also note- 

 worthy points. 



Scapolite Amphibolite, Maxwell's Crossing, Township of 

 Glamorgan, east side of Lot 5, Range VL. 

 (Section 1272). 



This is a fine-grained, eminently crystalline, and some- 

 what friable rock, of dark greenish-gray color. It is 

 foliated and banded, broad or narrow bands of the darker 

 constituents alternating with bands which contain the 

 lighter ones. 



The microscope shows it to be composed essentially of 

 scapolite and hornblende, though in some bands consider- 

 able calcite and pyroxene are seen, and in others indi- 

 viduals of plagioclase are common ; a little quartz also 

 occurs. As accessories, it contains numerous small 

 wedge-shaped or irregular grains of nearly colorless 

 sphene, which are much cracked, and many small, well- 

 formed crystals of apatite, which in prismatic sections 

 sometimes show the basal parting. 



Plagioclase is in good sized individuals, quite fresh, 

 often untwinned. It is an acid labradorite, having a 

 specific gravity of about 2.69. Calcite is distinguished by 

 its rhombohedral cleavage and the silvery tints in which 



1. Eosenbusch, H. ( op. cit., pp. 158 and 294. 

 Harker, A., op. cit., pp. 284-286 and 296-298. 



