A combination of these three methods is found in the Dry-blowing Machine.
It has always been a hotly debated question, whether what is known as the “Cement” comes under the heading of “reefs” or “alluvial.” This cement is composed of angular quartz-fragments, broken from the reefs or veins, and fragments of diorite and hornblende schists, cemented together by lime; it is very hard and solid and, in places, continues to a depth of over twenty feet. The gold is extracted from these depths by crushing and dry-blowing. I have mentioned this peculiar composition last, as I am not at all clear to which class of formation it belongs.
At first this cement, which the shallow alluvial ground overlies, was supposed to be “bottom,” that is to say, that there was considered no likelihood of gold being found at a greater depth. Later developments, however, have proved this theory to be wrong, and with regard to this I cannot do better than quote extracts from a report made by Mr. E. P. Pittman, Government Geologist of New South Wales, in which he says:—
He had considered the question of deep-leads of alluvial, and after visiting Coolgardie, Kalgoorlie, and Kanowna, he thought it probable that there would shortly be a large output of alluvial gold from this source. In Coolgardie the dry-blowing had been confined to a very shallow depth, and yet close to Coolgardie—in Rollo's Bore—there was evidence of the existence of a very deep valley. He produced a specimen, taken by him from an alluvial working near the Boulder Mine, showing what the dry-blowers had all through regarded as the natural floor of the alluvial. Below this floor they had never penetrated until the enterprising prospector at Kanowna recently did so, and followed the lead down to fifty feet.
…He was satisfied that the alluvial went down to a depth at Kalgoorlie just as it did at Kanowna. All the conditions were favourable to deep-leads of alluvial.
…Rollo's Bore at Coolgardie had proved the existence of alluvial gold at great depths.
…So far the alluvial men had been working on a false bottom.
At the time of writing, some two thousand men have found profitable employment in working this newly discovered deposit; and doubtless conditions similar to those found at Coolgardie, Kalgoorlie, and Kanowna, will be proved to hold on other alluvial fields, formerly supposed to be worked out.
How hotly debated this “cement question” has been may be judged from the fact that, at the time of writing, riots are reported from Kalgoorlie, during which the Premier was hooted and stoned. This cowardly act could hardly be the work of genuine diggers, and could doubtless be traced to the army of blackguards and riffraff who have, of late years, found their way to the goldfields.
It would be idle to discuss here the questions of “who is right” and “who is wrong.” A great deal can be said on both sides. Let us hope the controversy will be settled to the satisfaction of both parties; that the diggers will not be turned off what is justly theirs, to benefit leaseholding companies, nor leaseholders deprived of their rights.