708 
■WELiiiNGTOJf Eeep, Chaetees Towees (Qtjeejtsland) . 
Prom 600 feot vertical depth. Portion of core from diamond drill. 
Section. — Quartz shows fewer and smaller inclusions, sometimes very minute 
and red (haematite probably). Bpiclote and magnetite as before. A little apatite, hut 
less than in the four previous rock samples ; orthoclase and microcline, the former 
being often filled with flue particles of mineral matter polarizing in high colour. Vide 
Eosenbusch on “ Epidote.” * 
The other felspars are much decomposed and difficult to identify. The orienta- 
tion in most of the felsj)ars is undulose. This was the first of a series of rocks that I 
sliced in Charters Towers, and is hardly thin enough for microscopic examination, the 
quartzes all polarize in a deep purple colour, owing to this, whereas in the previously 
described samples from Charters Towers, the quartzes are all light yellow or lavender. 
The hornblende is much replaced by minerals of secondary origin, viz. — epidote, 
chlorite, magnetite, and viridite. 
Noeth Axistealian Eeef, Chaetees Towees (Queenseakd). 
Prom deep ground. 
Tlie special characteristic of this rock is the very large amount of hornblende 
present. Unfortunately I have only the slice, which is too thick, as it belongs to a 
group of rocks similar to the preceding. 
There are two varieties of hornblende, a grass-green species with feeble 
absorption for rays vibrating parallel to an axis of elasticity. Then there are some 
granules with very irregular outlines, whose greatest length and breadth would not 
exceed 'Ol inch, whose pleochroism is very marked, ranging through green, yellow, and 
rose-pink to red, in the course of a quarter revolution of the stage. At one position of 
the stage the centres will be surrounded by zones of different colours. These, from 
the high refractive index, should be epidote. The other species of hornblende is brown, 
showing well-marked cleavages, with an angle of extinction of 14° 40' to these cleavages. 
In other examples of the hornblende the extinctions with regard to cleavage, fall to 0 . 
Absorption very strong for rays vibrating parallel to cleavages. The felspars show a 
high angle of extinction ( — 29° 40' on P.) Therefore there must be much anorthite 
present, as indeed is: shown in the following partial analysis of a Charters Towers 
granite published in the Annual Eeport of the Mines Department for the year 1887. 
'The sample is from the Court-house Eeserve, and was dressed up from a boulder at 
surface. The sample looked quite clean, and was not perceptibly weathered. 
SUica '72-00 percent. 
Iron 
Alumina 
Lime, CaO 3 '22 „ 
Loss on ignition ... ... ... ... ... 0'50 „ 
The iron and alumina together present in the sample weighed over 20 per cent. 
No attempt was made to ascertain whether the iron was protoxide or ferric oxide. 
The felspars are twinned on the albite and pericline law, and often highly 
kaolinized. Orthoclase rare. 
The quartzes are full of inclosures, and the same description given in Nos. 240 
to 243 applies here. 
* “ Microscopical Physiography,” p. 286, 
+ Brisbane : by Authority : 1888. 
