1865 was the year that chemists breathed new life into NSW’s ailing gold mining industry.

It didn’t happen all at once – in fact the breakthrough announcement came late in the year. But for its significance and importance in what was to unfold on the NSW fields over the decade ahead, this single discovery in the laboratory was to unlock vastly more riches than any new goldfield announcement could ever conceivably rival.

The problem you see had all to do with Mercury – not the planet, but rather that most ancient and ambiguous of metals that had an amazing ability to grab hold of any gold passing by – at least most of the time.

Mercury was at that time the be all and end all of the gold recovery process for any pulverised material emerging from a stamper mill. Accordingly if you wanted to look at the key problems holding back reef gold mining, look at how much gold got washed by the mercury and lost in the tailings.

The essence of the problem with the gold recovery proces using mercury was succinctly described in an article in the Sydney Morning Herald in late 1865 as follows ...

“The process of amalgamation has been carried on with great success in various parts of the world with ores yielding as little as half an ounce of gold per ton, wherever those plagues of the metallurgist, sulphur and arsenic, are not present.

Whenever either of these elements exist in an ore – and this is the case with by far the larger proportion of gold ores – they have the effect of tarnishing or “sickening” the mercury, as the miners call it, the consequence being that a large percentage of the gold in the ore is unacted on and lost.

The loss of gold from this cause is very great, varying from 30 to 87 per cent, of the metal present. In some experiments by Readwin 2 cwt. of rich quartz gave hardly any gold by the ordinary process, no less than ten ounces of gold remaining untouched in the tailings.

On this account it has been found impossible to work several even of the richest mines. In practice, too, there are several well known cases where grains of gold were visible in the quartz, and little or none was extracted by amalgamation.”

15th September 1865

The problems all stemmed from the fact that after quartz, pyrite (iron sulphide) is the most common mineral asociated with gold. While reef gold near the surface had often lost much of this sulphide content due to natural weathering, it reappeared once the mines got a bit deeper.

One of the only ways to deal with this was to bake the ore prior to crushing it to drive off the sulphides and free up the gold. The challenge here was to get the ore hot enough to do any good.

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3rd October 1865

Amongst the many problems associated with roasting pits was that even if you could get them hot enough to be effective, they were a significant extra capital expense to set up and then an ongoing cost to operate.

This is why the simple cure for “mercury sickening” was such a breakthrough. It by no means ended the problem of gold being lost in the tailings, but it did ensure that enough was captured at minimal cost to make reef mining a profitable venture in many cases.

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This chemical breakthrough could not have come at a better time for the NSW goldfields, which by now were in a state of transition from the boom and bust alluvial days, to the capital intensive, rigorous work required to develop reef gold reserves.

While news of new goldfield discoveries across south west NSW continued to filter through regularly, many of these failed to live up to their early promise.

Meanwhile many of the old workhorse fields like Tambaroora just kept quietly on with a settled population investing where and when they could in their deep mining ventures.

18th February 1865

It was telling that by the start of 1865, news of the former star fields like the Lachlan workings at Forbes and Burrangong field at Lambing Flat, were fast fading in media reports.

In their place the Lucknow field near Orange excited attention and helped to refocus interest back on the original heartland of the NSW fields adjacent to Summerhill Creek.

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17th May 1865

In this climate, it was left to a remarkably detailed letter to the paper in May of that year to provide a general summary of the state of the NSW gold industry over the previous seven years.

Included in this account is a serious geological description of the gold-bearing country and also the fact that many other minerals besides gold were associated with these strata.

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6th September 1865

It is significant that as gold lost some of its all commanding presence in the public mind, commercial interests also began to focus their attention on the other minerals of the region.

This came through strongly in one correspondent’s account from September that year, prior to him then going on to focus on the detailed workings of the Wentworth / Lucknow field.

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11th September 1865

Moving on, this same correspondent noted that it wasn’t the lack of reef gold that held mining back – rather a lack of the necessary investment.

“The quartz reefs … extend over nearly the whole of the country lying between Stoney Creek and the Macquarie, and may be seen cropping up in the ranges at every twenty or thirty yards. Hardly any of these have been tried without giving at the very least from 8 to 10 dwts. to the ton, an amount which, in the absence of powerful machinery, and with the cost of carriage, will not pay at present.”

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25th October 1865

But to fully appreciate the parlous state of the existence of the Chinese on the Burrangong field at Young at this time, and the effects of the racially discriminatory legislation that was brought in to restrict their activities to portioned off sections of the field, one need go no further than this letter of October that year.

At least the events recorded here had moved the author to change his position of animosity towards the ‘Celestials’.

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21st December 1865

As year 14 in the life of the NSW goldfields drew to a close, there was little to excite the attention of the media. Once again the gold news started out with its rivetting introductory line of “Little news of any interest from our goldfields”.

Those who managed to read on however would have noted a very interesting addition to the close of the article. There an “OTHER MINES” section appeared with news on related mining activities including copper and kerosene shale – times were indeed changing.

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