CUPRIFEROUS PORPHYRITE AND QUARTZ VEINS. 59 
were offshoots from an igneous mass which once covered 
the sedimentary rocks but is now removed by denudation. 
Such an hypothesis fails to account for the small veins 
which are so abundant in the Nelligen district, whereas 
the hypothesis that their quartz and gold are derived from 
the original sediments by metamorphism accounts for both 
the small veins and large reefs which behave in the manner 
described. The metamorphic rocks of the Nelligen district 
are of considerable interest including zoisite schist, mica 
schist, biotitic schist, epidotic schists and many other varie- 
ties of schist which I intend to give an account of later. 
I hope shortly to visit the district again and to be able 
to give to this Society a general account of the many points 
oi interest in the physiography, general geology, economic 
geology and petrography of the country between Nowra 
and Nelligen and the Pigeon House Range. 
* PeTROLOGICAL Note.—The cupriferous basalt is a porphyritic, 
rather decomposed, olivine-basalt. The base is fine grained and 
microcrystalline. The phenocrysts consist of felspar (plagioclase), 
The constituents of the base are plagioclase, augite (decomposing 
to uralite and chlorite), olivine and magnetite. Secondary chlorite 
is plentiful. This rock was therefore a somewhat acid basalt 
before decomposition set in. It contains no olivine phenocrysts. 
Name. Porphyritic andesitic basalt. 
