334 -  ,. Gs TAYLOR AND D. MAWSON. 
Other dolerites of the district.—F¥ine specimens for rock 
section purposes can be obtained from the Nattai River 
cliffs, just north of the incline terminating the Mittagong 
Coal Co’s. tramline. Microscopically the sections are seen 
to contain plagioclase, augite and magnetite, with accessory 
calcite and apatite. The various rocks are characterised 
by special texture or constituents. Thus in B. 23, under 
high power, beautiful little hexagons of a brown mineral 
can be seen. These are most probably micaceous hematite. 
Many of the dolerite masses have what appear to be less 
basic dykes (aplitic veins ?) running through them, B. 22 
is of this type, consisting mainly of plagioclase. The 
dolerites from Jellore Creek approach picrite in composition. 
Augite and magnetite get more plentiful, while much 
serpentine is present. Pyrites often occurs as grains and 
prisms (H. 45). Chlorite showing pitted structure is com- 
mon in some slides from this locality. 
No. 6. Locality Jellore Creek at foot of Mount Jellore. 
(Plate 26, fig. 3.) 
Hypidiomorphiec granular. 
Texture 
Fabric—No base is present. The rock consists of an 
intimate mass of augite, felspar and ilmenite. 
Minerals present (> by weight. Rosiwal’s method)— 
Augite ... a a he Hes soe SG 
Felspar ... ai ie ae ee J.) Aa 
Ilmenite... £G she fe: We we 28 
Apatite—accessory 
Serpentine | 
Calcite > secondary 
Analcime ) 
The chief characteristic is the prevalence of ilmenite in 
long narrow ragged crystals representing sections of the 
usual tabular habit. The long axes are very approximately 
parallel, indicating perhaps some flow while the magma, 
