28 



Case 50. 7521, from the Star Lead, Gulgong, has been ohtainei at a 

 depth of 195 feet. A specimen of the basalt which covers the 

 Grulgong deep lead is also exhibited. 



2140, Gulgong, and others show gold freely ; these are 

 exceptionally rich specimens.* 



In washing alluvial material to save the gold, various other 

 heavy minerals are sometimes obtained — e.y., zircon and iron- 

 sand. 3759, Tumbarumba, and others consist of this black-sand, 

 Eeacli-sands. as it is called. The gold and platinum bearing beach-sands in 

 Case 48. case 48 (page 21.) really belong here. These sands are found at 

 numerous spots along the K'ew South Wales coast, more particu- 

 larly in the north. They consist of material that has been brought 

 right down to the sea by rivers. They contain a very large propor- 

 tion of zircon sand. Now, zircon is a dense mineral, nearly twice as 

 heavy, bulk for bulk, as ordinary quartz sand. It is consequently 

 practically icnpossible to separate it from the gold by washing. 

 Only the very fine particles of gold have finally reached the sea- 

 coast, and these have been beaten out into fl:it discs during the 

 lengthened journey from the parent rock. 40S9 reprtsents 

 these grains, and it wdll be readily understood how these 

 fl.attened grains will tend to float on the surface of the water, 

 thereby increasing the difficulty of saving it. 6749 and others 

 are from the so-called McAulay's Lead, a former beach-deposit 

 that has been cut on" from the present coast by the formation of 

 lines of wind-blown sandhills. Such deposits now constitute 

 swampy country, and have been stained brown and become 

 loosely coherent by the action of vegetable matter. A_ large 

 block of sand-rock, perforated by boring stells, will be found in 

 case 128. While mucli of the gold can be saved by amalgama- 

 tion with quicksilver, there has until lately been no satisfactory 

 method of extracting of the platinum. All that could be done 

 was to concentrate the sand as much as possible. Tinstone is 

 sometimes present in considerable quantities in these sands. 



* Alluvial deposits can sometimes be successfullj' worked whsn fhej do not contain more 

 than a few grains ot g-old to the load of wash-dirt. 



