104 Supplementary Notes on the Diabase Rocks 



mineral (Rubellane), the final stage being to a hydratecl ore 

 of iron.* All these Diabase rocks belong to the same 

 formation, and the same period of time as those I have 

 described as occurring to the eastward of the Murendel 

 River, and also at the Snowy River. 



The Limestones. — On these Diabase rocks rest conform- 

 ably about 150 to 200 feet of the Buchan limestones. I 

 collected and examined examples from the places marked 

 (f) and (g). 



These are all composed mainly of carbonates, whose yellow 

 colour indicates the presence of iron among their bases. The 

 carbonates are confusedly aggregated together as masses of 

 rhombic crystals, including numerous angular fragments of 

 quartz crystals, and of pieces of more or less altered 

 porphyrite rocks. Here and there spaces are filled in by 

 choritic minerals. 



These limestones, without doubt, represent the passage beds 

 which I have before described as connecting the upper and 

 lower divisions of the Buchan beds. 



The Faults. — The group of formations which I have now 

 briefly described are cut off on the western side by a double 

 fault shown upon the diagram section as (x) — (x l ). The 

 eastern fault of the two is, I suspect, a continuation of that 

 on which the workings of the Murendel Mine have been 

 carried on. 



Such faults as these seem to be common in the district. 

 Perhaps to speak more correctly, I might say that such 

 faults are more easily recognised in the Buchan district, 

 where the succeeding formations differ so much from each 

 other than in other parts of North Gippsland, where are 

 found only the Silurian series, and the igneous rocks which 

 have intruded into it. 



The faults at Murendel seem to me to have an essential 

 relation to the ore deposits. In their neighbourhood the 

 rocks of whatever kind are seen to have been more or less 

 altered. The quartz porphyrites have been least affected ; 

 the Diabase rocks most so ; and the limestones have, as a rule, 

 been bleached and crystallised. All the rocks traversed by 

 these faults near Murendel have been more or less impreg- 

 nated with ores of various metals, and in certain places the 

 deposits of ore have been such as to induce mining com- 

 panies to attempt working them. 



* See Progress Bepoi't, No. 5, Geological Survey of Victoria, p. 143. 



