BY W. N. BENSON. 697 



magnetite. Mr. Cotton, at first, classed the tourmaline-granites as 

 a modification of the acid granites (op. cit.), but he now considers 

 them to be a separate intrusion. He found them near Tingha. 

 Mr. Stonier has reported them to occur "east of Bingara," and 

 the present writer found them near New England Creek, east of 

 Manilla, 50 miles south of Tingha. 



(10) The lamprophyric rocks are of uncertain age and affinities. 

 They intrude into Devonian, and probably Carboniferous rocks, 

 forming small dykes, and all the occurrences noted are within a 

 few miles of the serpentine-belt. In the absence of definite evi- 

 dence to the contrary, they will be considered to be a late phase 

 of the granitic intrusion, as is usual. The rocks collected, show a 

 considerable range of character, and may be referred to several 

 types. The minettes are represented by M.B., 145, occurring in a 

 dyke near the contact of granite and serpentine at Attunga. It is 

 a dark, medium to fine-grained rock, with glistening mica-plates. 

 It contained abundant idiomorphic biotite, decomposing with 

 separation of magnetite and diopside in well defined prisms, 

 slightly uralitised. The felspathic constituent is chiefly orthoclase 

 in singly twinned prisms or more irregular grains, while a minor 

 amount of oligoclase is present. Interstitial quartz occurs in 

 small amount, and apatite is abundant. There is a little secondary 

 calcite. The analysis indicates the strongly potassic character of 

 the rock (Table iii.). 



A very fine minette [M.B., 200] occurs about one-quarter of a 

 mile south-west of Eumbra homestead, Crow Mountain (Plate xxvn., 

 Fig. 14). It forms a small intrusion in the mudstone, beside an 

 intrusion of dolerite, but the relation of the rocks to each other 

 has not been ascertained. Unfortunately^ the minette is very 

 decomposed and friable. It consists of coarsely granular ortho- 

 clase, and abundant, hexagonal plates of strongly pleochroic bio- 

 tite, containing minute zircons. Small, idiomorphic prisms of 

 diopside, thick needles of apatite, and a very little interstitial 

 quartz are also present. 



The vosgesites are more abundant, and have been found on the 

 Frenchman's Spur, near Nundle [N.T., 190, 317], and on Tom 



