Generally, mining and exploration is undertaken with some idea of what might be found at the end of the excavation. Hopefully, a very specific idea. But the planet, and the human beings upon it, are still capable of throwing up a few surprises for the worthy geologist.
Klerksdorp Spheres
Were they planted deep in the earth by mischievous aliens hoping to confound the planet’s geologists? Er, no. But Klerksdorp Spheres do look strangely manufactured, and it’s easy to see why over-imaginative conspiracy theorists have branded them as ‘OOPArt’ (Out Of Place Artifacts). These small, reddish brown, flattened discs reach up to 10 cm in diameter, and often have three parallel, clearly defined ridges running around their circumference.
They generally have a metallic sheen, and when cut open, exhibit a radial structure. In many ways they do look fashioned by hand, but despite that distinctive appearance, the spheres are actually concretions formed by the precipitation of volcanic sediment and ash.
They were initially discovered by miners working the pyrophyllite mines of Ottosdal in South Africa. (If you’re down that way, there is a museum featuring them in the town of Klerskdorp about 70km away.) They’ve been dated to 3 billion years.
Since their discovery, the spheres have been variously identified as dinosaur eggs, alien artefacts, a new form of metal never before seen on Earth, and, according to one ‘investigation’, are so perfectly balanced that they could only have been made in zero gravity… Hmmm, well, sadly, not the case, and not even alone. Moqui Marbles from the Navajo Sandstone of Utah and Moeraki Boulders in New Zealand are both similar examples of natural spherical concretion.
Kyawthuite
The rarest mineral on Earth, so rare, in fact, that only one example of it exists, discovered in the Mogok region of Myanmar. It’s a deep orange crystal, with the formula Bi3+Sb5+O4 (a natural Bismuth Antimonate). Legend has it (unverified) that it was discovered by gem prospectors in 2010 who had no idea what they had on their hands, and sold it to a geologist collector at a local market.
It’s now held at the Natural History Museum of Los Angeles County. Little is known about it. Even the manner of its formation is uncertain, but artificial versions have since been successfully created.
Dozens of 1930s cars
In 2016, Belgian PE teacher Vince Michel was roaming an abandoned quarry in central France when he discovered a mysterious cache of rusted 1930s cars, hidden away for 70 years, and parked two or three abreast at the bottom of a mineshaft. Enquiries revealed that they had been requisitioned during WWll when Germany forces had occupied the country, then forgotten when the war came to an end. There are numerous Citroens, Renaults and Peugeots amongst the collection. Most have been left in a peace to honour their owners, but a few rarer items have since been brought to the surface.
Wolfsegg Iron
Also known as the Salzburg Cube and another OOPA.
This small cube of worked iron was reportedly discovered at Austria’s Braun iron foundry, when workmen broke open a block of lignite to find this lump of metal inexplicably at its centre, covered with a thin layer of rust.
It was originally identified as being meteoric in origin, but is now less prosaically thought to be a chunk of cast iron, often used as ballast in early mining machinery, that was dumped and somehow made its way into the seam.
Painite
If it wasn’t for Kyawthuite, then Painite might well steal the place as the world’s rarest mineral. It’s found in only a few locations globally – again mostly in Myanmar. Following its discovery by British gemologist Arthur Pain in the 1950s, it was for many years considered the Holy Grail of gemstone rarity, with just four crystals being unearthed between 1956 and 2001.
It’s also considered very beautiful, with a deep red colour and a structure that shows off a variety of hues and shades from different angles.
In 2005 an outcrop of painite was discovered, and many hundreds of stones mined, but still just a few cut gems exist in the hands of collectors. What makes it so special is the uncommon natural combination of elements zirconium and boron essential to its formation. The complete chemical makeup includes calcium, zirconium, boron, aluminium and oxygen, plus trace amounts of chromium and vanadium.
An entire church made of salt
The Salt Cathedral of Zipaquira lies 200m down in a Columbian salt mine, and started life in the 1930s as a spot for salt miners to say their daily prayers before heading off to work. But in the 1950s a much larger excavation project got underway, including naves and an enormous cross. That became unsafe and was eventually shut down, but a new Cathedral, 200ft below the old one, and away from the working mine, was started in 1991 and inaugurated in 1995. You reach it via 14 chapels, again built entirely from salt, before ending under a huge dome and a nave 80m long, complete with choir stalls.
Thousands of tourists now visit it every year, but while religious ceremonies take place, it doesn’t have a bishop, so isn’t officially recognised as a cathedral within the Roman Catholic church.
Pepita Canaã
The world’s largest surviving gold nugget, discovered by miner Julio de Deus Filho in Brazil’s Naked Mountain gold region in 1983, as part of the Serra Pelada 1980s gold rush. At just over 60kg gross weight it’s as heavy as a man, and contains 52kg of gold. However, it’s not the biggest ever, just the largest still in existence, (on display at the country’s Banco Central Museum in Brasilia.)
That claim to fame goes to the Welcome Stranger, found in Australia’s Victoria goldfields in 1869, weighing in at 72kg and located only a few centimetres down in the roots of a tree.
Such was its size that it was immediately broken up before any records or photographs could be taken. With a perhaps more interesting and better recorded history was its predecessor in size, the Welcome Nugget, discovered 11 years earlier in the roof of a tunnel 55 metres below what is now the modern city of Ballarat in Victoria.
The group of Cornish miners that discovered it had been the first to introduce steam-driven machinery to the region’s gold mining industry. Yet it was actually found by a labourer swinging a pickaxe while everyone else was off having lunch. He struck the nugget, realised what it was, and promptly fainted. For a while the Welcome Nugget toured Australia and London, the wonder of amazed tourists, before being sold to the Royal Mint who used it to produce gold sovereigns. A scale model of its 68kg, 50cm length can be found at Mebourne’s Museums Victoria.