er dd aa 
XXX.—NOTES ON THE ANCIENT AND RECENT MINING 
OPERATIONS IN THE EAST OVOCA DISTRICT, sy P. H. 
ARGALL. Puates 12 and 13. 
(Communicated by G. H. Kinanay.) 
[Read March 17th, 1879.] 
Introduction. 
Ir is proposed to describe in this communication the mineral 
lodes and mines in the country east of the Ovoca river, but with- 
out giving more than a short sketch of the geology of the dis- 
trict. 
Many years ago the geology of this area was described in a 
paper read by Mr. Thomas Weaver before the Geological Society 
of London (vol. v., 1st series). Other early writers have also 
written on it; while in later years it has been examined more in 
detail by the officers of the Geological Survey (Profs. Oldham, 
Smyth, and Jukes, and Messrs. Wyley, Du N oyer, and Kinahan). 
From the researches of these gentlemen we learn that the rocks 
in which the mineral lodes occur belong to the Cambro-Silurian 
or Lower Silurian formation. 
Formerly it was supposed that the minerals occurred in beds 
which were deposited contemporaneously with the existing rocks ; 
but recent researches have shown, that although in gencral the 
direction of the lodes is more or less close to that of the strike of 
the rocks, yet the lodes always cross the beds, though sometimes 
at a very small angle; in depth the lodes always underlie at a 
greater angle than the rocks. 
The rocks of the country are principally killas (slates and shales) 
which are all slightly metamorphosed ; but associated with them 
are felspathic and pyroxenic rocks. All the pyroxenic rocks are 
supposed to be intrusive, some being very granitic (Granitone) ; 
There are some remarkable peculiarities connected with the 
felspathic rocks. Weaver, in his writings, calls some of them 
hornstones, others quartz rocks, while more recent writers have 
elassed them as siliceo-felspathic rocks and felstones. They were 
supposed at one time to run parallel with the mineral channel ; 
but Professor Smyth has pointed out that in some places they 
SciEN. Proc., R.D.S., Vou. u., PT. 111, Q 
