325 



map. Some occur as veins in the main granite. The first 

 occurrence noted is in the first gully south of the Cape 

 • Willoughby Lighthouse. The dyke outcrops at the head of 

 the gully, and has a width of eight yards. Its boundaries 

 are ill-defined and are covered with sand. In hand specimens 

 it is a coarse aggregate of blue quartz and white felspar, 

 apparently not graphically intergrown. 



A second pegmatite with predominant felspar and show- 

 ing strings of quartz is well developed on the northern side 

 of Barn Bluff. Limonite is associated with the felspar in 

 parts as a subsequent alteration ; muscovite is also present. 

 The rock has weathered out into honeycombed masses. 



The remaining occurrences of this rock are in the form 

 of veins, which outcrop on both sides of Pink Bay, along 

 the coast. They vary in width from 2 ft. downwards, and 

 vary in composition from an aggregate of blue quartz and 

 white felspar to veins of pure felspar. For the most part 

 these veins run parallel to the trend of the joint planes in 

 the granite. 



The three types of .minor intrusion occur as separate and 

 distinct masses. In no case have they been observed in asso- 

 ciation, to enable their order of intrusion to be determined. 

 These, too, were the only types of intrusions seen exposed in 

 the granite mass. 



Minor intrusions into the neighbouring quartzites were 

 not observed ; about seven miles from Cape Willoughby a 

 pegmatite dyke is developed in schist. Gem tourmaline has 

 been derived from this area, and the dyke is most probably 

 an offshoot from the Willoughby mass. The writer had not 

 an opportunity of visiting this locality. 



Microscopically, the minerals present in the pink aplite 

 are quartz, microcline, plagioclase (albite), and, as accessories, 

 biotite (much chloritized), and muscovite. Kaolin and 

 secondary mica accompany the felspars as alteration products. 



One slide shows a well-developed phenocryst of plagioclase 

 as a trilling, and, in addition, albite lamellae are present. 

 This is probably an oligoclase albite. It is surrounded by a 

 beautiful micrographic intergrowth of quartz and microcline. 



The micrographic intergrowths are displayed more 

 especially in the coarser varieties of the intrusion. In these, 

 also, apatite begins to appear and muscovite is more plenti- 

 fully distributed, often in plumose fashion. Some of the 

 albite shows twinning after both albite and pericline laws. 

 In the finer-grained types' the fabric approaches the type 

 "granulitic" characteristic of some aplites. 



In an aplite near Pink Bay, related to this series, 

 subidiomorphic grains of magnetite appear, and in addition 



