57 



to Hadley, where they will meet the train again. This 

 represents a distance of five miles (8 km.) 



The road going south from McCue's crossing first 

 crosses drift with a few exposures of the white crystalline 

 limestone protruding through it. 



This is succeeded by the nepheline syenite, the actual 

 contact of the rock with the limestone being obscured by 

 drift. About the middle of the nepheline syenite belt, the 

 road passes over an included body of limestone. 



A variety of nepheline syenite rich in albite and 

 poor in nepheline is exposed in the low cliffs on the east 

 side of the road one mile north of Hotspur Corners on lot 

 1 6, range IX of Monmouth. 



Under the microscope it is seen to possess a hypidio- 

 morphic structure and to consist of the following minerals: 

 Albite, microcline, microperthite, nepheline, lepidomelane, 

 magnetite and calcite. In some few schlieren a dark green 

 hornblende (probably hastingsite) replaces a portion of the 

 biotite. Albite and lepidomelane are the chief constituents. 

 The albite is well twinned and must be a variety approach- 

 ing the pure soda molecule, as it has a specific gravity of 

 2-6i8 and shows a maximum extinction against the line 

 of the twinning lamellae of 15 . In a single slide a few 

 grains having an extinction as high as 20° were observed, 

 showing that a plagioclase somewhat more basic than 

 albite is also occasionally present in very small amount. 

 The microcline presents its usual characters and is fre- 

 quently intergrown with albite, forming microperthite. 

 The nepheline is in large individuals similar in shape and 

 dimensions to those of the albite. Smaller individuals of 

 it are sometimes included in the albite, while in other 

 cases it includes individuals of albite. It is very fresh 

 and free from alteration products. The lepidomelane is 

 the same dark brown, highly pleochroic variety of biotite 

 which occurs in the transitional rock lying between the 

 granite and the nepheline syenite and has the same form 

 of short laths. A lighter coloured mica is also present in 

 smaller amount. The calcite occurs in large single indivi- 

 duals, often rounded, sometimes enclosed in the feldspars, 

 nepheline or lepidomelane, but usually lying between the 

 other constituents. The enclosing minerals show no 

 signs of alteration and the calcite shows no sign of secondary 

 origin. The magnetite is in large subangular or more or 

 less rounded grains. There seems to be no definite order 



