ROGERS, GEOLOGY OF THE CORTLAXDT SERIES 51 



The writer has observed several other instances, however, which would 

 •seem to merit description. The pale-green pyroxenite recorded above, 

 occurring on the border of a limestone inclusion, is undoubtedly a contact 

 fades, and may be recalled in this connection. 



Wernerite Schist 



Wernerite schist is found in a small patch at the cross-roads on Mon- 

 trose Point, lying in the pyroxenite area. It has been only partly ex- 

 posed by the excavation of an old clay pit at this point, but it probably is 

 not more than several hundred feet long, extending northeast. In the 

 field, it is distinctly gneissoid in appearance, the black bands being very 

 distinct. It is very tough and has been planed off into a series of roches 

 moutonnees, so that it is hard to sample. Under the microscope, it is 

 seen to be made up of scapolite, pyroxene, titanite, calcite and pyrite. 

 The scapolite seems to be wernerite, and the appended analysis as recast 

 indicates that it is Me 4 Ma 15 which is a very calcareous wernerite. The 

 mineral gives conclusive tests. It makes up almost three fifths of the 

 rock. Associated with it is the calcite, which is very subordinate in 

 amount. The pyroxene is similar to that found in the green pyroxenite 

 described above, except that the grains are less crowded and have a pris- 

 matic shape. They are regularly aligned, and impart the gneissoid ap- 

 pearance to the rock. The pyrite and titanite are very variable in amount, 

 occasionally becoming quite abundant. Since all of these minerals have 

 been observed on the limestone contacts, there is little doubt that this 

 patch represents an entirely absorbed inclusion of limestone. It is pos- 

 sible, of course, that the limestone is still present, though concealed, but 

 the rock described exists over a zone 75 feet wide, at least. 



Lying between this rock and the pyroxenites, in several places at least, 

 a typical diorite is to be found. 



On Verplanck Point, just west of the brick yards, and about 200 feet 

 from the schist contact, a pyroxenite exists whose peculiarities might be 

 taken to indicate a similar history. The rock is very hard and black, 

 although in thin section a surprising amount of alteration is revealed. 

 There is considerable pinkish angite in the rock, which appears to have 

 altered largely to a greenish hornblende. Wernerite is present to the 

 extent of nearly one third, in large and small grains. 38 Calcite is less 

 abundant, and in part at least, it is derived from the augite. There are 

 also biotite, apatite and plagioclase in small amounts. Although no 

 limestone is visible near this rock, the wernerite would point to an in- 

 cluded patch which had been partly or wholly absorbed. 



36 F. C. Calkins (Science, XXIX, 946. 1909.) notes the occurrence of "primary" 

 scapolite in igneous rock, but also concludes that it is due to the absorption of limestone. 



