BY W. N. BENSON. 689 



as are seen among the gabbros, with which they are probably 

 genetically connected. A series of rock exist, however, which 

 show increasing amounts of quartz, and approach to a panidio- 

 morphic structure, thus exhibiting some resemblance to certain 

 of the lamprophyres. 



The following may be considered as typical examples — M.B., 

 225 : intrusive into the serpentine, five miles south of Crow 

 Mountain. In hand-specimen resembling the Nundle dolerites, 

 medium grain-size, and dark greyish-green colour, with grey and 

 pinkish felspars. It consists of rough idiomorphic augite, making 

 up about one-half the rock-mass. It has usually a large, optic, 

 axial angle, but, in one instance, this was only 65 a . Hence 

 there may be some excess of the enstatite-molecule present. It 

 is partly converted to actinolite. The felspar is slightly zoned, 

 and is basic andesine; a little orthoclase is present, and possibly 

 a little quartz. A similar rock [M.B., 229] intrudes into the 

 serpentine at Crow Mountain, and is noteworthy for the presence 

 of a clear zone of secondary plagioclase (andesine) around each 

 felspar-prism. 



The dyke of dolerite in the serpentine at the Paling Yard[M.B., 

 68], and that three miles south of Gulf Creek [M.B., 194], on the 

 eastern side of the serpentine, differ from the above in their 

 greater approach to panidiomorphism, and the abundance of the 

 interstitial quartz, either granular [M.B., 194] or granophyric. 

 Small veins of prehnite occur in the Paling Yard rock. 



There are others, however, which are quite free from quartz. 

 A dyke in the serpentine on Eumur Creek [M.B., 198] consists of 

 plagioclase, and small, roughly idiomorphic augite, giving a 

 granulitic structure. This felspar is very clear, and the augite 

 quite undecomposed. It occasionally has sahlite-striation, but 

 the optic, axial angle is always large. Veins of prehnite are 

 abundant, and small, isolated patches of the same mineral occur 

 throughout the rock. A little pennine and titanomorphite are 

 also present. M.B., 187, from the same locality, appears exactly 

 similar in ordinary light, save for the greater roughness of the 

 50 



