Dugald & Colin at the Little Wonder on Chelo farm, 1936
Zimbile is situated on one of the so-called 'gold belts' of Matabeleland, an interesting area geologically and riddled
Ore from the Little Wonder (Emma)
Peter panning for gold
Dugald, Toots Borchards
Panning for gold
with isolated pockets of gold-bearing rocks. Old shafts and diggings are common in the area and naturally as children
growing up on Zimbile we would devote part of our holidays to crushing rocks and panning for colour, extracting little
tailings of gold with mercury and making little buttons of gold in the forge at the workshop.
The old mortar box from the two stamp mill at the Little Wonder (by then abandoned) proved to be the most rewarding for these activities and by scraping and washing out the crushed residue a fairly substantial lump of gold was eventually recovered. Naturally, after this windfall, the more meager rewards resulting from carting rocks from old shafts on the farm were less attractive.
During the 1970's I spent a good deal of time developing transparent thin film metallic and ceramic coatings for a South African company making architectural glass for modern skyscrapers. Historically these films were made of gold, an efficient coating for reducing the heat of solar radiation from buildings and reducing the load placed on air conditioning. With the oil crisis in the early 1970's the price of gold rocketed and new products had to be found. Gold was eventually replaced by some transition metal alloys and ceramic nitrides of titanium.
During a period between jobs in 1983, for some or other reason that I can't remember, I came across the old buttons of gold that I had kept as mementos of the farm and decided to make try my hand at making some jewelry. I had, too, some small pellets of gold and odd bits of all the metals of the periodic table that I had brought home for the children to use in their school science projects. I scratched out some likely looking pellets and the buttons from the farm (together about 3 oz), wrapped them in lead foil to absorb the impurities and (no longer having access to lab facilities) heated them with an acetylene torch in a small crucible.
I was surprised to have great difficulty in melting the gold (mp 1063 deg C) and eventually ended up with a rough gold lump that was really extremely hard, like tungsten. On trying to re-melt it I found that it was totally unworkable and I couldn't do so. It wouldn't dissolve it in any of the recognized solvents, chlorides, etc, so I just had a hard yellow lump. I realized that I had inadvertently contaminated the gold with some titanium.
I wasn't working at the time and so I phoned a pawn broker who was looking for old rings, etc. for the trade. (It's illegal in South Africa to be in possession of raw gold so we came to an understanding that he would buy the gold but forget who he got it from).
I didn't think any more about it until about a month later when he phoned me up and asked me, what had I done to the gold? He had given it to the CSIR, who confirmed that it was indeed gold but had no idea of why it was so refractory! I explained that it was an alloy of gold with 2-4% titanium (and that I thought it likely that any gold alloy with a small %age of any of the transition metals would also be refractory).
A few months later I saw a short article in the local paper that a new gold-titanium metal alloy had been discovered by the CSIR. I did a Google search the other day and found several references to titanium-gold alloys. So, seems the Little Wonder has an enduring legacy after all.
Gold geology, Southern Rhodesia (Collender-FD-1965-PhD)