THE PETROGRAPHY OF SOME QUEENSLAND OIL SHALES. 
129 
The groundmass is made up of humosite and matrosite, and is continuous 
throughout the rock, surrounding the gelosite and retinosite bodies, it is 
considerably greater in amount than that of the Alpha torbanite. 
Chemical Analysis. 
A proximate analysis of this sample has given the following result : — 
Moisture at 105 deg. C. . . . . . . 3-0 % 
Volatile Matter . . . . . . . . . . 45-5 % 
Fixed Carbon . . . . . . . . . . 20-6 % 
Ash 30-9 % 
Chemically this indicates a low to medium-grade torbanite. As with all 
melanocratic torbanites the ratio of volatiles to fixed carbon is less than 10 to 1. 
THE NARROWS OIL SHALE. 
General and Macroscopic. 
Locality of sample chosen for study : From 225 ft. in Munduran No. 1 
Bore, The Narrows. Parish of Rundle, county of Deas Thompson, approximately 
20 miles N.N.W. of Gladstone. Geological Horizon: The Narrows Tertiaries. 
Age : Probably Miocene. 
In the hand specimen this is a fine-grained, smooth, even-textured rock 
of pale greyish-brown colour. It is distinctly laminated, the laminations being 
quite finely developed. It has a dull lustre and breaks with a hackly fracture. 
It is soft but moderately tough, and gives a greasy pale brown streak. The 
specific gravity is 1-56. Thin flakes of the rock ignite with some difficulty when 
heated with a match and burn with a smoky yellow flame. 
From the above description it is apparent that the rock is a low-grade 
oil shale. 
Microscopic. 
(Plate XII, figs. 3, 4.) 
Horizontal and vertical sections of this rock have shown that it is made 
up principally of very finely divided clay, together with a smaller amount of 
organic material. The clay is intimately associated with some of the organic 
matter and, under ordinary transmitted light, the whole clay matrix shows a 
strong yellowish stain. Scattered through this matrix are small, irregularly- 
shaped, organic masses of a dark reddish-brown colour. This material, which 
may reasonably be classified as semi-opaque attritus derived from the decay 
of vascular tissue, makes up about 20 % of the rock. These semi-opaque masses 
are irregular but generally more or less elongate in shape, and range in length 
from approximately 0-01 mm. to 0-35 mm., their average length being about 
0-05 mm. Presumably the translucent humic attrital material has been macerated 
to various degrees, some forming the jelly which impregnated and stained the 
clay matrix. An intensive search has failed to reveal any spores or algal bodies 
in the thin sections of this oil shale. Most of the organic matter then has 
come from vascular material. 
