Spinifex and Sand 14Part 4 · Quartz Reefing and Dry-Blowing
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Literature · Western
Spinifex and Sand 14
Part 4 · Quartz Reefing and Dry-Blowing
CarnegieEnglish
I would not, even if I had the requisite knowledge, wish to bore the reader by giving a scientific account of gold-mining, but Western Australia presents so many appearances differing from those in other gold-producing countries, and so varied are some of the methods of obtaining gold, that I hope a short account of the usual ways of winning the precious metal, purely from a prospector's point of view, will be of interest.
The area over which the goldfields extend, may be described as very gently undulating country, from which rise, at intervals, low ranges or isolated hills.* These ranges, in reality seldom over 200 feet above the plain, have in the distance a far more important appearance. It is a common experience to steer for a range, sighted from perhaps a distance of fifteen miles, and find on closer inspection that it is no more than a low line of rocks. It is equally common for a hill to appear as quite a respectable mountain when seen from one point, but entirely to disappear from view when seen from the opposite direction, so gentle is the slope.
[* Mount Burgess, the highest hill around Coolgardie, is about 500 feet above surrounding country.]
These ranges, such as they are, occur at intervals of a few miles up to thirty or more, and between them scrub-covered plains, sand-plains, or flat stretches of open forest are found. In the deeper undulations, long chains of dry salt-lakes and samphire-flats are met with, occupying a narrow belt, perhaps one hundred miles in length. Doubtless were the rainfall greater, these lakes would be connected, and take the place of rivers, which would eventually find their way into the Australian Bight. Unfortunately for the comfort of travellers, this is not the case, and their water supply must depend upon one or other of the various sources already described.
The first aim of a party of Western Australian prospectors is to find not gold, but water. Having found this they make camp, and from it start short excursions in all directions towards any hill that may be in sight. Arrived at the hills, which, though bare of undergrowth, are usually covered with low scrub, they can soon determine from the nature the rock whether further search is likely to have good results. Should they see hills of ironstone and diorite, or blows and outcrops of quartz, they will certainly revisit the locality. In what manner, will depend upon the distance from water. They may be able to form camp in the desired spot, with water close at hand; or the party may have to divide, some camping in the likely country, engaged in prospecting solely, while the others "tail" the horses or camels at the watering-place and pack water to their mates. In cases where "good gold is getting," water has sometimes been packed distances of twenty to forty miles; or it may happen that good country must be passed over, from the want of water within reasonable distance.
From his limited appliances and means, a prospector's object is to find a vein or reef of gold-bearing ore, not by sinking, but from surface indications.
Veins or reefs may be described as layers, which have been deposited in fissures and cracks in the rock surrounding them. The enclosing rock is known as the "country rock." "Lodes" are veins composed of a mixture of quartz, ironstone, and other material, and usually exceed in width the "reefs," which sometimes, as at Southern Cross, attain thirty feet, but are rarely more than one to four feet in thickness. The part of a reef showing above the surface is the "outcrop," which may appear either as a mass or "blow" of quartz, sometimes sixty feet in height, or as a solid wall or dyke which can be followed for perhaps five miles without a break; the direction in which it runs is known as its "strike."
Reefs may go down vertically, or on a sloping "dip" or "underlay." The country rock lying immediately above the reef is the "hanging wall," and that immediately below, the "foot wall."
In prospecting a reef, a miner walks along the strike of the outcrop, "napping" as he goes, i.e., breaking off with a hammer or pick, pieces of the quartz or ironstone outcrop. Each fragment is carefully examined for the presence of gold, which is nearly always found, if on the surface, in a free state, that is to say, uncombined with any other mineral. If any gold is present, it may occur in small specks as fine as flour, or in large solid lumps as big as one's fist, as in Bayley's Reward Claim, Londonderry, and one or two other mines. In the latter case the rich find would immediately be pegged out as a claim, or lease, and work commenced, the coarse gold being won by the simple process of "dollying" the ore; or pounding it in an iron mortar with an iron pestle, and passing it when crushed, through a series of sieves in which the gold, too large to fall through, is held.
To estimate roughly the worth of a reef in which only fine gold is visible it is necessary to take several samples along the outcrop, "dolly" them, and wash the powdered quartz by means of two iron dishes, from which the light material is floated off, leaving the gold behind. From a series of experiments an idea can be formed as to whether the reef is worth further work.
It will be found on napping a reef, that the gold occurs at more or less regular intervals. This deposit of gold in the surface outcrop is the top of a "shoot" of gold, which may be followed down on the underlay for many feet. And this peculiarity in the distribution of the metal has been the cause of much disappointment and misunderstanding.
Having determined that your reef is good enough on the surface, the next thing to be done is to ascertain, by means of cuts and shafts, its nature below the surface. This may be done either by an underlay shaft, which follows the reef down from the surface, or by a vertical shaft, sunk some distance away from the outcrop, to cut the reef perhaps one hundred feet below.
By a series of shafts with drives, or galleries, connecting them when they cut the vein, a more accurate estimate of the value of the reef can be made.
Now in the case of a reef which has rich shoots a prospector, naturally anxious to make his "show" as alluring as possible to any possible buyer, sinks his trial shaft, on the underlay, through the shoots. And so it might happen, that by carefully selecting the sites of his shafts, he might have a dazzling show of gold in each one, and merely blank quartz between them. A mining expert, usually only too ready to give a glowing report, makes his estimates on the assumption that the quartz intervening between the shafts is as rich as that visible in them, and the purchase price increases accordingly.
Not only do shoots occur to puzzle the expert, gladden the heart of the prospector, and madden the shareholder, but the eccentricity of gold is further exemplified by the way in which it has been been deposited in "pockets."
No better example of this could be given than the Londonderry Mine, where gold to the value of many thousand pounds was won from quite a small hole in the outcrop. At the bottom of this hole lumps of solid gold could be seen, and inasmuch as other pockets, equally rich, had been found, it was assumed by nearly all concerned that the reef was a solid mass of gold, and the whole community was mad with excitement. However, when the purchasers started work, it was soon discovered that the golden floor to the golden hole only continued golden to the depth of three or four inches, to the despair of the promoters and unlucky shareholders, as well as of the numberless adjoining leaseholders, through whose property this rich reef had been traced.
It seems incredible that a vein should run in more than one direction, and yet it is made to do so, and to go North, East, South, or West, or to any intermediate point of the compass, at the discretion of those responsible for the prospectus! An unmistakable surface outcrop is not popular amongst experts (it leaves no scope for the exercise of an elastic imagination), whereas they cannot be expected to see under ground, and can then make their reef run in the most suitable direction.
I do not think the much-abused expert is any more dishonest than other folk, though he has more temptation. His bread and butter depends on his fee, his fee depends, not on the accuracy of his report, but on the fact, whether or no that report suits his employers. If, as often is the case, he has to report on a "lease" whose only value is derived from its close proximity to a rich show, and if that rich show only appears above the surface in an isolated mass, and its direction of strike can only be guessed at, and, above all, if he knows that his fee or future employment depends on guessing that direction into the property under report, I think he has been led into temptations from which most of us are exempt, and which a good many would find it hard to resist. The term "expert" refers only to the numerous army of "captains" and "mining experts" of mushroom growth, for which the soil of the goldfields is so suitable, and is not applied to the mining engineer of high standing, whose honourable and straight dealing is unimpeachable.
Having brought the mine to such a state that it is ready to be purchased, in which unsatisfactory position it sometimes remains for many long months, I will now leave it, and will not touch upon "mills" and "batteries," which are the same, or nearly so, in all countries, and are outside the province of a prospector, who, from his limited capital, is unable to erect the costly machinery necessary for the extraction of gold from quartz on a large scale. Therefore the prospector parts with his mine as soon as he can find a purchaser, usually an agent, who sells at a profit to some company, which in its turn sells at a greater profit to the British or Australian public.
The humbler prospector confines his attention to alluvial gold, that is to say the gold which has been shed from the outcrop of the reef, by weathering and disintegration. The present small rainfall, and the evidence from the non-existence of river-beds, that the past rainfall was no greater, go to show that this weathering is due to the sudden change in temperature between night and day, the extreme dryness of the atmosphere, and strong winds. Without any rush of water it is not possible for any great depth of alluvial soil to have been formed, nor can the gold have been carried far from the reef, or reefs, in which it has its origin. For this reason, though exceptionally rich in places, the alluvial diggings have never been either of great extent, or depth, or of general richness.
In many places the alluvial soil is not more than a few inches in depth. It is in such places that "specking" may be carried on, which consists in walking slowly about with eyes to the ground, and picking up any nuggets that may be seen. Many thousand ounces of gold have been found in this simple manner. Where, however, the alluvium is deeper, a considerable amount of labour must be expended before gold can be won. In countries blessed with abundant rainfall the nuggets can be separated from the dirt by a comparatively simple arrangement of sluices and cradles. In the drought-stricken west of Australia other means must be adopted, which I will endeavour to describe.
Having picked and dug out a certain amount of the alluvial ground which, it is hoped, contains nuggets of various sizes, the digger then breaks up any lumps of clay or earth by means of a heavy billet of wood, or like implement, and this prepared dirt, as it is called, he treats in one of the following ways:--
1. BY MEANS OF TWO IRON DISHES, in diameter 15 to 18 inches, and in depth 4 to 5 inches.
One dish is placed empty on the ground, the other, filled with the prepared dirt, is held up at arm's length above the head, with the mouth of the dish turned to the wind; the earth is then allowed to fall gradually into the dish beneath, all light particles and dust being blown away by the wind. Exchange of dishes having been made, the same process is repeated again and again. When there is only a small amount of dust left, the full dish is held in both hands, and given a circular movement, which causes the larger stones or pebbles to come to the surface; these are cleared away with the left hand, and a sharp look out is kept for nuggets or quartz specimens. This is repeated until nothing is left in the dish but a small quantity of dust, ironstone-gravel, and possibly fine gold, or small nuggets. The dish is then held up at an angle, and shaken from side to side until a compact little heap remains, to the bottom of which the gold will have sunk. The next and final operation is to hold the dish up to the mouth nearly horizontally, and blow the little heap across the dish. Any fine gold will then be seen lying on the bottom just under the nose of the operator.
Given a good hot summer's day, flies as numerous as the supply of water is scanty, clouds of dust, little or no breeze, and the same quantity of gold, and a few score of men working within an area of nine or ten acres, one is sometimes tempted to think that gold may be bought too dear. But the very lowest depths of despair, cannot compare with the heights of satisfaction, attained after a successful day's "dry-blowing."
2. BY MEANS OF TWO DISHES, AND A TRIPOD STAND AND PULLEY.
A tripod, twelve or fifteen feet high, is set up over a hard and smooth piece of ground. By a rope and pulley the full dish is hauled up as far as required; the rope is then made fast and a string, fixed to the edge of the dish, is pulled, and the dish tipped up allowing the dirt to fall on to the prepared surface below, where it is swept up and treated as in the first method described. With a fair breeze this is a very effectual way of getting rid of the fine dirt.
3 BY MEANS OF A SIEVE.
This method is only suitable when the soil is wet and sticky, or where the nuggets are fairly large and not too rare.
On the first rush to Kurnalpi, where more alluvial gold was found in a short time than on any other field, sieves were almost the only implements used.
A sieve is very useful for prospecting the surface soil, being more portable and more rapidly worked than the dishes.
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.
