Rocks of Noyang. 57 



(b) Foliations alternating with (a), composed of the first- 

 mentioned colourless uniaxial mineral, together with flakes 

 of a brownish yellow mica, which in places predominate 

 almost exclusively. 



(c) Black granular material, most of which I judge to be 

 carbonaceous — possibly some may be magnetite. This is 

 heaped together in places. 



Another slice prepared from a sample which was not so 

 markedly foliated, I found to be composed almost entirely of 

 the chlorite-like mineral, with here and there isolated flakes 

 of colourless mica (muscovite ?). These were disposed in two 

 directions, so as to produce a net-like effect in the slice. I 

 observed herein also a few stout short prisms of green 

 tourmaline, and much carbonaceous material, and some 

 hydrated iron ore. 



In none of these samples did I observe the thorn-like 

 microliths which are so plentiful in some slates. 



In proceeding up the course of the Tambo River from the 

 Noyang ford, the contact of the igneous and sedimentary 

 rocks is found at the junction of that river and the Haunted 

 Stream. In following up the Tambo from this point the 

 appearance of contact metamorphism decreases, until the 

 hornfels rocks gradually are replaced by highly inclined alter- 

 nating sandstones and slates of much the normal appear- 

 ance and strike. In selecting a sample for examination I 

 endeavoured to choose one which should be as much as 

 possible in an unmetamorphosed condition ; for, at a short 

 distance northward, the formations again show change, and 

 this time gradually assume a character which places them 

 with the regionally metamorphosed schists of Omeo. 



The beds from which I selected a sample had a strike of 

 N 55° W. I found them fine-grained and fissile ; in colour a 

 dark green, but in all cases slightly spotted by the peroxida- 

 tion of their iron. A thin slice which I prepared did not, 

 however, bear out the impression I had received from an 

 inspection of the rocks in position. The uniaxial colourless 

 chloritic mineral which is so common a constituent of many 

 of these fine-grained rocks was almost absent, and its place 

 was taken by another colourless micaceous mineral, in 

 rounded plates, with often ragged edges. This mineral, 

 although biaxial and somewhat resembling muscovite, does 

 not polarise with the brightness of that mineral, which also 

 exists in small amount in the same rock. The double 

 refraction of this mineral is rather weak. 



