116 PROCEEDINGS OF TPIE ROYAL SOCIETY OF QUEENSLAND. 



districts {see N. T. Bulletin No. 16). The blue auriferous 

 quartz occurring in the hornblendites has been sheared ; it is 

 frequently crossed by veins of white quartz, and is found 

 principally as small leaders which are usually very rich in gold. 

 Many of these leaders have been worked at the Maid of Erin 

 Hill and Trig Hill, Pine Creek. The writer has not yet had a 

 chance to examine the pre-Cambrian amphibolites of North 

 Queensland, but Rands's description of the Ebagoolah goldfield 

 shows that there is a close similarity between this field and the 

 Northern Territory goldfields. In the Coen and Ebagoolah 

 fields one would expect to get the same two types of quartz as 

 in Western Australia and the Territory. 



Graphite in Lodes. — The widespread distribution of graphite 

 in the lodes of Western Australia, the Territory, the Cloncurry 

 district, Ebagoolah district, Croydon, &c., is one of the pro- 

 nounced features of the north-central massif. The writer has 

 shown (N. T. Bull. 16, and in an official report on Croydon not 

 yet published) that the graphite is probably of chemical 

 origin, due to interactions between limestone, hydrogen, water, 

 and iron minerals at high temperatures with probably iron- 

 carbonyl as an intermediate product of the reaction. He can 

 see no reason for the belief that any of these graphites have 

 been derived from coal seams. In studying the Gympie 

 graphitic beds under the microscope, the writer found the 

 plumbagiferous beds derived from tuffy limestones (submarine 

 ■calcareous tuffs) with marine fossil remains rather than plant 

 beds, while the lode graphites of other districts are probably 

 of hydato -igneous origin. In other parts of the world, as in 

 Ceylon and in the New York province, graphites occur 

 chiefly in highly metamorphic rocks, and are probably of 

 hydato-igneous origin.* 



In the Northern Territory, on the margins of the great and 

 igneous intrusions, and, in general, on the strike lines of the 

 pre-Cambrian crystalline limestone belts, as at Krana Creek 

 (Margaret district), Uwatha Tableland (Upper CuUen River), 

 we get frequent large areas of andalusite and chiastolite- 

 sillimanite rock, very rich in grapliitic carbon {see N.T. Bulletin 

 16). There can be little doubt that this graphite was formed 

 chemically from the metasomatism and silicification of cal- 

 careous carbonate rocks, and limy shales. 



* See " The Origin of Graphite," by H. I. Jensen, D.Sc, Economic 

 "Geology, Jan.-Feb. 1922. 



