141 

 Notes on the Gem-bearing Gravels at Barossa. 



By D. Mawson, B.E., B.Sc. 

 [Read September 7, 1909.] 



Plate VI. 



Amongst a sample of gravel and pebbles obtained from 

 the auriferous wash in the Barossa Ranges, and recently sub- 

 mitted to me, I found several saleable gem-stones, in addi- 

 tion to a large variety of valueless chips. A record of these 

 latter is serviceable, as indicating their occurrence in situ 

 amongst the crystalline schists and gneisses of the district. 



This find is specially noteworthy, as having yielded the 

 largest gem-quality ruby and the largest rough sapphire yet 

 definitely recorded in South Australian territory. 



Gem-stones of various kinds have been reported (i) widely 

 distributed in this State, though little of commercial value 

 has yet come to light. 



Some of the more important of these are the following : — 

 Beryl, variety Aquamarine,i'^) occurs in the form of crystals 

 embedded in quartz reefs and coarse quartz felspar reefs in 

 the Mount Lofty Ranges, notably in the Barossa District. 

 More recently I unearthed an important occurrence at Albe- 

 gudina Creek, on Bimbowrie Station, about twenty miles 

 north of Olary. There the crystals occur embedded in white 

 quartz reefs, and were found measuring up to 5 in. in diameter 

 and 1 ft. 6 in. long. In all these occurrences the beryl is 

 light coloured, and usually so much flawed as to be useless. 

 However, good cuttable aquamarine and more deeply-coloured 

 stones have been got from the workings near Williamstown. 

 Small crystals only about |^-in. in diameter of the variety 

 emerald occur embedded in a tourmaline-bearing aplitic 

 granite on the south bank of the South Para River, south- 

 east of Williamstown. 



Translucent tourmaiine of excellent quality has been 

 found in coarse granite pegmatite, notably on Kangaroo 

 Island, <3) where both ruhellite and indicolite have been 

 mined. 



An extensive formation of corundum schist carrying the 

 coloured varieties has been reported by Mr: H. Y. L. Brown 

 from Mount Paynter,(4) but so far this locality has yielded 

 no cuttable stones. 



(DVide "Record of the Mines of South Australia," 4th ed., 

 1908, p. 358, by H. Y. L. Brown, Government Geologist": PuF^ 

 lished by authority. 



(2) Vide ibid, also "k Catalogue of South Austrahan Minerals," 

 by T. C. Cloud. Trans. Roy. Soc, S.A., vol. 6. p. 72. 



0)IUd, p. 360. 



WlUd, p. 358. 



