162 R. A. Far quhar son— Petrology of N. Kalgoorlie, 



a much chloritizedform of the non-phenociystalporphyrite. The grey 

 or brown areas are resolvable under high powers into aggregates of 

 minute brown-yellow rutile prisms and needles, so that these areas 

 no doubt represent original ilmenite, or less probably biotite. 



The structure of the rock is rather indefinite. It resembles that of 

 the fine-grained ophitic dolerites, but also that of the non-phenocrystal 

 porphyrites. The rock is difficult to place, but has been put 

 provisionally amongst those of doleritic affinities. 



12387 is a greyish-green rock with veinlets of quartz, with much 

 carbonate, and with a somewhat sheared structure. The minei'al 

 constituents are chlorite, quartz, carbonate, and apparently some 

 kaolinic material. In places forms are visible which by ordinary- 

 light resemble large decomposed zoned plagioclase crystals, but which 

 by polarized light appear as mixtures of quartz and carbonate. 

 Prisms and grains of brown-yellow rutile are scattered all over the 

 slide, as also are small plates of clear quartz. 



The rock shows no structure. It appears more allied to the 

 diorites than to any other group. 



12303. A weathered, dirty red and green rock of rather coarse 

 texture. Minerals observed : epidote, chlorite, quartz, magnetite, 

 apatite, and some rounded areas rendered rii sty-red by ferric oxide. 



There is a total absence of structure. The slide is a mineral mass 

 in which the commonest mineral is a yellow and greenish-yellow 

 epidote in plates and platy aggregates. With the latter are partially 

 chloritized fibrous and strongly pleochroic collections of greenish 

 hornblende forms, while in many places are patches of greenish 

 chlorite. Quartz occurs in large clear cracked plates; there is much 

 magnetite, and there are occasional apatite needles. In one place 

 a turbid form resembling a columnar felspar is visible. The rock was 

 with little doubt formerly an amphibolite. 



JEpidioritic RocTcs. 



Both 2950 and 11001 are specimens too much decomposed to call 

 for description. They appear, however, to be composed of fibrous, 

 sheafy, and divergent aggregates of a pale hornblende which has 

 subsequently been partially altered to chlorite. They are both with- 

 out normal igneous structure, and are, in consequence, set down as 

 weathered epidiorites. 



C. The Talc-Chlorite Eocks of moke indefinite origin. 



The rocks of this group are those composed largely of talc and 

 chlorite, but of which the origin is doubtful. They vary in 

 colour from red to dense black, but are commonly green. They 

 are all soft. 



3391. A blackish-green rock, with few recognizable minerals. 

 Seen in section it consists of numerous fine fibres of a colourless 

 mineral with low refractive index and high double refraction. Some 

 radial extinction in sheaf-like aggregates is also to be observed. 

 Grains of magnetite are frequent, as are patches of granular carbonate. 

 Though in hand specimens the rock is serpentinous in character, 



