44 Rocks of Noyang. 



sinuses ; this was followed by a rather narrow envelope of 

 felsitic basis ; the third envelope was of radial masses of 

 the usual spherulitic composition. The whole mass was 

 surrounded by a very fine-grained crystalline compound of 

 felspar and quartz, in which there were a few small radial 

 spherulites. 



Throughout the compound ground-mass are innumerable 

 small, lengthened green or brown niicroliths, some bent or 

 twisted, or with forked ends. They occur more frequently 

 in the spherulitic than in the micro-crystalline-granular 

 parts of the rock. So far as I could observe their direction 

 of extinction forms a small angle with the longer diameter. 

 This suggests that they are amphibole, and the original con- 

 dition of the chlorite microliths which I have found to be so 

 numerous in the ground-mass of the quartz-mica-porphy rites 

 of this locality. 



In this ground-mass are porphyritically (1) crystals of 

 quartz, (2) crystals of plagioclase, (3) a few examples of 

 chlorite pseudomorplis after magnesia-iron-mica. All these 

 porphyritic crystals are of the character of those I have 

 described as occurring in the quartz-mica-diorites. 



(2.) A dyke crossing the road north of Noyang. 



This dyke cuts across the quartz-mica-diorites about a 

 mile from the ford, and is probably a continuation of one of 

 the strong dykes which have been laid bare by floods, in 

 Navigation Creek, possibly even of the dyke which I have 

 examined and analysed, as recorded on page 25. 



In this sample the main mass is micro-crystalline-granular. 

 In it are distributed small prisms of plagioclase and granules 

 of quartz. Besides these there are spherules isolated and in 

 masses. Some of these are composed only of radiating long 

 and very narrow prisms ; others are radiating bundles of 

 fibres surrounding a central crystal of quartz or felspar ; and 

 others are formed of a radial hemisphere placed against a 

 felspar crystal. 



(3.) Rock at the ford at Noyang. 



This rock is composed wholly of felspar and quartz. The 

 constituents of the ground-mass are arranged in radial 

 aggregates. When such an aggregate is placed in a certain 

 position as regards the plane of polarisation, one or other of 

 the constituents becomes wholly obscured at the same time, 

 and the second constituent stands out in strong contrast. 

 This structure, therefore, assimilates to that which is called 

 " micro-pegmatoide" by MM. Fouque and Levy. These 



