224 PROCEEDINGS OF SECTION C. 
Contact metamorphic deposits are usually associated with 
acid rocks or rocks of medium basicity. 
Several of these deposits are known in Tasmania. At the 
‘Shepherd and Murphy Mine,* in Middlesex, a garnet epidote 
rock occurs, which is plainly a product of the contact 
metamorphism of the granite and a limestone bed. Certain 
portions of this rock are very highly charged with magnetite, 
which is often present in practically solid bands running 
through the stone.. This rock is traversed by one of the 
Shepherd and Murphy tin veins, the walls are sharp and 
well-defined, and it is evident that the tin vein is younger 
than the metamorphic rock and its contained magnetite. 
In the Comstock district, near Heemskirk, on the West 
Coast of Tasmania, there are a large number of contact 
- metamorphic deposits. Here they take the form of huge 
masses or lodes of magnetite, often beautifully crystallised, 
and associated With a coarsely crystalline light-green coloured 
mica, which has not been accurately determined. Some of 
these deposits contain a good deal of zinc-blende and some 
galena. The deposits have not yet been carefully examined 
geologically. In the same district there are several big 
lodes (the Comstock and South Comstock, the Kynance, 
&e.) which contain payable quantities of zinc-blende and 
galena. I am at present, however, unable to say whether 
these have any connection with the contact deposits.+ In 
the North Dundas district also there are deposits of mag- 
netite near the contact of quarfz tourmaline porphyry, with 
highly contact metamorphosed slates, which in all probability 
are to be referred to this class. 
These contact metamorphic deposits are, perhaps more 
certainly than any others, of true pneumatolitic origin; for 
they were ejected from the granite while it was still in a 
molten condition. Beyond this, however, we know very 
little of the processes which preceded their formation. Even 
the state of combination of the metals when they were in 
the gaseous condition is not known. In the case of the next 
two classes of deposits which we will have to consider, we 
are justified in the conclusion that the metals were combined 
with flourine or chlorine, as minerals containing these 
elements are very abundant in association with the metals; 
but in the case of contact deposits we have no such clue. 
*G. A. Waller. Report on the Mining Districts of Bell Mount, 
Five-mile Rise, &c. Mines Dept., Tas. 
+ Since the above was written I have had an opportunity of 
examining the ore deposits of the Comstock district. A report 
thereon will shortly be issued by the Mines Department of Tas- 
mania.—G.A.W., 25.1.03. 
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