Gold Specimens from Bendigo. 165' 



ness of the quartz vein diminishes, and becomes almost pure 

 gold. An interesting feature of the specimen is shown in the 

 illustration, and consists of a number of gold platy riffles stand- 

 ing out from the vein at right angles to the wall. These riffles 

 are on the whole parallel to the cleavage of the slate, and repre- 

 sent gold that has been deposited in the cleavage cracks from 

 solutions traversing the course of the vein. The feature exists 

 on both sides of the vein. It is very clear from this specimen 

 that the slate has been a precipitating agent for the gold. 



Another specimen from the same gold shoot, and the same 

 mine, can also be recorded, though it does not lend itself to 

 illustration. It was obtained from the 1264 feet level, adjoining 

 the plane of a small west dipping fault. A spur, which varies 

 in thickness from -J inch to IJ inches, butts against the fault 

 plane, and contains pyrite and colours of gold. Projecting from: 

 the wall of a small branching spur, which forms the fault plane,, 

 is a nest of pyrite cubes, and the wall of the fault and spur is 

 mostly covered with a film of gold, which also extends into the 

 fractures of the associated slate. These two specimens are rare,, 

 and at first glance the films of gold paint suggest the occurrence 

 of secondary gold, i.e., gold which has been leached from the 

 gold-bearing spurs, and precipitated by the slate. The small 

 fault is believed to have existed prior to the vein formation, and 

 gold might have been precipitated from the primary solutions- 

 circulating along it, or from subsequent secondary solutions. The 

 great depth of the occurrence of 1264 feet below the surface- 

 is a fact in strong opposition to a theory of downward secondary 

 enrichment, while the association of the gold with the sulphides 

 is more consistent with its being of primary origin. Even if it 

 were claimed that these occurrences indicate the presence of 

 secondary gold, it must be remembered that they are rare. Fre- 

 quent inspections of mining operations on this gold shoot in the- 

 Carlisle mine, which, during the fourteen months preceding Sep- 

 tember, 1921, produced 15,712 ounces of gold, valued at £84,761, 

 failed to yield any evidence recognisable as being characteristic 

 of secondary enrichment. It may therefore be fairly concluded 

 that the gold in the spurs is primary, and that the existence 

 of the gold shoot is dependent on primary causes. 



