QUARTZ MINING

Korero (AEWS), Volume 2, Issue 8, 24 April 1944, Page 18

QUARTZ MINING

A KORERO Report

One day in 1906 three old miners were prospecting the bed of a creek high in the hills behind Reef There

was gold in the creek, but though they had panned out a few colours (as one still can in many West Coast streams) they had not yet struck it rich. With the patience and energy of the old-time diggers they kept at it spurred on by the hope that soon they would find gold beyond their dreams. And find gold they did. In the brown waters of the creek (Waiuta, or black water, the Maoris called it) they struck a reef of gold-bearing quartz. It yielded them a few ounces, but it was not what they had hoped to finda rich patch of alluvial gold that could be worked without need for greater capital than ingenuity, patience, and hard toil. Besides, who could say how far the reef would run and how deep. Maybe only a few feet below the depth they had worked. So, miner-like, they sold their claim for £6OO and began again their search for El Dorado. The sale was made to a mining speculator, who gave an option to purchase to mining interests who later formed “ The Blackwater Mines, Ltd.” Up to this date practically nothing had been done to prove the extent of the reef by mining, beyond a few small holes along the reef-line from the surface. The option holders did considerable prospecting of the reef, including over 1,000 ft. of driving, and, having satisfied

themselves that the width, length, and values disclosed a promising mining undertaking, exercised their right of purchase outright for They then proceeded to form the present company.

Thirty-six years ago the old prospectors saw Waiuta Hill as an area of virgin bush. To-day it is the site of a picturesque village and the home of some four hundred people. Unlike the alluvial goldfields of the Coast that attracted thousands to mushroom towns that flourished a few years and then died, the quartz reef at Waiuta has produced payable quantities of gold for many years, and even now, when the reef has been followed to a depth of half a mile, there are no signs that it will peter out. To-day two high shaft heads and large buildings housing complicated machinery mark the location of the reef. And far below the creek-bed from which the old-

timers picked out the auriferous quartz, pneumatic drills bore into the earth and gelignite tears down the white reef, which is lifted from the depths to the treatment plant on the surface.

The white quartz reef which carries the gold dips down through the earth from south to north and also leans at an angle from east to west. The reef itself varies in width from 2 ft. to 5 ft., averaging about 2 ft. 6 in. Throughout its vertical depth there are many faults where, because of the earth’s pressure, a piece

has been bitten out of the reef or the reef itself broken off and pushed to one side. When a fault is struck the only thing to do is keep blasting. Normally the reef is soon relocated, as it usually returns to its general direction. Once it was lost for several weeks, and its disappearance caused some consternation. The mine is worked in levels. A shaft is sunk beside the reef and tunnels bored in at depths of about 150 ft. to strike the reef. Then main tunnels, called levels, are worked out to the boundaries of the reef. Then the reef is followed throughout its length up to the level above. This is done by “ stoping.” Working from the main level, subshafts, called “ rises,” -are cut, and up these the miners climb to sub-levels which they cut along the line of the reef. By

"stoping” they blast out the quartz and mullock that surrounds it and drop the quartz to the main level below through a timbered chute. Then, using the loose spoil to fill in the ‘‘stope from which the quartz has been removed, they move above the area mined and work back along it at a higher level. Thus, instead of the huge chasm indicating the area from which the quartz has been taken, you find open only the main levels plus the area in which the miners are working. The narrow tunnelsa little more than the width of the reef and between 5 ft. and 6 ft. in height—are timbered throughout their length with stout wall and roof props. The timbers are left in the main levels and constantly repaired except in the old levels long since worked out, where they are left to rot.

The miners work in pairs • drilling the quartz-face, laying and firing the “ shots ” and shovelling the spoil down the nearby chutes to the level below. They use pneumatic drills, with a water-jet near the bit which wets the quartz and stops the fine dust from rising. “ Shots ” are fired only at stated times for the whole mine, and the miners need not return to the face for twenty to thirty minutes after blasting in order to give the quartzdust time to settle. Fine water-sprays are used to assist the settling process and disperse the fumes.

This dust, if it reaches the miners’ lungs continuously and in sufficient quantity, will bring on the dreaded miners phthisis hardening of the lung tissues. Under modern conditions if precautions are taken, the risk of contracting it is small.

From the levels above which the miners are working tramways run back to the main shaft. The spoil is trucked from the chutes in the ceiling of the level and the linked trucks are taken by a small electric trammer, called a “mule,” to the main shaft. Here there are two double-decker cages, one descending as the other ascends. In these the loaded trucks are taken to the surface in about two minutes.

"What sit like down there ? You drop 2,600 ft. in about four minutes, six of you to a cage roughly like that of an elevator, except that there’s nothing but a waist-high gate on two sides. If you don t keep your elbows in you get them badly barked. The cage is lowered by a steel wire rope and kept in position on wooden guides. The yawning black mouths of old levels flash by as you descend, There is a slackening of the cage’s descent and then you stop at one of these black mouths and clamber out into a widish tunnel where full trucks are waiting to be taken to the surface. The light from the acetylene lamps attached to the party’s hats shows up a wet, low, timbered passage running off to the reef. Along the floor of the tunnel runs the tramway. It’s hot as hell as you

•clamber up a “ rise ” to the “ stope,” and hotter as you crawl along the narrow tunnel to the face on which the miners ■are working. Clad in trousers and singlet, with strong limbs shining with perspiration, they are busy shovelling the quartz down a ■” pass ” to the level below. If you kick a stone down the pass you hear it bounce from one side to the other of the chute sometimes for a good hundred feet. And these man-holes aren’t roped off. At times these “ passes ” are blocked by a stray piece of wood becoming lodged .across the shute, perhaps halfway down. The first sign of this is when the chute mouth is opened and no quartz falls through. A strong hose might remove the •obstruction or more quartz might be ■shovelled in on top in the hope that the ■extra weight might break the blockage. If these efforts fail, then its someone’s unenviable job to climb 40 ft. or 50 ft. up the narrow pass and discover what’s causing the hold-up. Then he sets a couple of sticks of gelignite amongst the spoil, praying that the obstruction holds the tons of quartz above it just a few moments longer, and after lighting a 6 ft. fuze scrambles down that chute far faster than he went up it. Ventilation is provided by air-boxes, which carry fresh air to where the men are working, and fans, which draw the air in at one shaft-head and out through the

other. The air goes down to the bottom levels first and works upward through the others. Thus the deeper you are the purer and cooler is the air. The miners generallywork to contract, being paid by the number of fathoms of reef removed. They are usually given a length of reef from 80 ft. to 100 ft. long as their “stope,” and the distances mined are measured periodically. Most

of the truckers are on contract at so much per truck. Shift bosses are on monthly salary. It’s tough work and not an ideal occupation for any one prone to claustrophobia, but the pay is good and though dangers seem real enough to the layman the experienced miner takes little notice of them. A piece of stone falling from the roof can give you a nasty knock, but the papier mache hats provide some protection and are light on the head. A steel helmet, though safer, would be far too heavy and hot for these temperatures. Danger is minimized through adequate timbering of the tunnels, and here there is a profitable industry allied to the mining. Every foot is timbered by the miners themselves as they drive their tunnels. The baulks are i ft. in diameter and 6 ft. 3in .high. Most of the timber needed comes from bush handy to the mine. Despite the reassurance of the shift boss that there is no danger of those millions of tons above you suddenly descending, the layman is quite glad to step into the cage and speed back again to the sweet safe air of the surface.