The cobalt time capsule of Alderley Edge

If you think trade sanctions, the battle for critical metals and the race to secure a local supply chain is all a modern headache, read on.  A recently discovered time capsule in the legendary heart of Cheshire, England, harks to a critical metals story from another time – the Napoleonic era’s original cobalt supply crunch.

 

The legend
An old Cheshire legend tells of a farmer who had a milk-white mare. On the way to the market at Macclesfield to sell her, as they reached Alderley Edge, the horse stopped and would go no further.

 

An old man with a white beard and a staff stopped by and offered to buy the mare, but the farmer refused. In Macclesfield many people praised the beautiful white horse, but no one would pay up. As they headed back, the curious old man was waiting for them at Alderley Edge, and he made his offer again. The farmer agreed, and the old man led him to a large rock. The old man touched the rock with his staff, and, by magic, a pair of iron gates sprang open in it. A path beyond led deep into the hill.

 

The farmer followed the old wizard into a cavern, where they saw 140 knights in silver armour lying fast asleep. A white horse stood beside all but one of the knights, and the wizard laid the farmer’s milk-white mare in an enchanted sleep next to the last knight. The knights, the wizard told the farmer, were waiting for the world’s last battle, and the wizard was to wake them when the time came.

 

The wizard led the farmer into the next cavern, which was filled with gold and silver and precious jewels, and told him to take as his payment as much as he could carry. Then he led him out with his treasure, and when the farmer turned around, the path, the gates, and the wizard were all gone, never to be seen again.

 

With time, the legend was interpreted to mean King Arthur’s knights of the Round Table, and the wizard destined to wake them for one last battle to be none other than Merlin.

 

Alderley Edge became a haunt of early 20^th century occultists, not least the infamous Aleister Crowley. Later on, it provided inspiration to the Alderley Edge-raised writer and folklore collector Alan Garner for his book The Weirdstone of Brisingamen.

 

While nobody ever tracked down the wizard or found the gates or the cave, if you happen to be in Alderley Edge, you can follow the National Trust’s Merlin’s Walk and visit the prehistoric Druids Circle hidden in the woods and the Engine Vein mine, one of the oldest in England. As for precious metals and stones, the caves and caverns below Alderley Edge are mines, mainly copper and lead, some dating back 4,000 years and among the oldest in the British Isles.

 

Tools found at the mines, now explored and curated by the National Trust, date back to the bronze age. The older mines feature square sectional shafts and tool marks that are distinctly Roman, and in he mid-1990s a hoard of Roman coins was found hidden behind the planks in a backfilled shaft.

 

We can blame the Romans for picking the place they called Londinium (London) to be the capital of England over the north-western city of Chester. And, oddly, the Vikings, the later foreign invaders that came to rule over Cheshire, did not appear to take much interest in Alderley Edge’s copper treasures. It is from the late Middle Ages, the 1500s that you can find the next wave of post-Roman mining trenches, followed by a resurgence of mining in the industrial era of the 1700-1900s.  It is this period that brings us the latest discovery in Alderley Edge’s mining history: cobalt.    

The discovery

Now owned by the National Trust, the Alderley Edge mines have been leased since the 1970s to the Derbyshire Caving Club, whose members maintain access and search for lost mines. The discovery of in late 2021 of a cobalt mine was accidental, Jamie Lund, National Trust archaeologist tells the MMTA. “When a vein was mined out there was no 20th century machinery, and it was not filled with concrete. The miners just packed it with sand and rubble and left it. With heavy rainfall, the sand gets washed away and the ground over a shaft begins to dish. So as soon as the rangers saw a dish forming they knew what it was, and put a call to the Derbyshire Caving Club.” What the cavers found was not a cave they could descend into, but a series of narrow tunnels, reinforced by rotten timbers, tracing what turned out to be a cobalt vein.

 

 

The tunnels offered a perfectly preserved time capsule of Napoleonic era mining: from miner’s shoes, a button, inscriptions in candle soot, an imprint of a worker’s corduroy clothing and clay pipes still lying abandoned on the floor, to clay bowls buried in walls, possibly by superstitious miners as a thanks offering for a rich vein, and to mine machinery. There was even a fully preserved windlass.

 

“The windlass still has a rope wrapped around it and even a hook at the end of the rope so you could see how it attached to a kibble (a bucket used to pull up ore from the mine shaft). There is even a ratchet in place that has been slotted into the teeth of the windlass so you can break the windlass if you need to,” Lund says.

“The objects will stay inside in the underground conditions that preserved them, having been photographed and catalogued. The old oak timbers are like a Salvador Dali clock, they are melting, akin to flowing liquid, so they can’t be moved.”

 

Instead, the National Trust commissioned Christians Survey & Inspection Solutions to photograph and film inside the abandoned cobalt mine using a drone. You can now take a virtual tour of the mine from the comfort of your armchair here: Later on a submersible might explore the lower, flooded mine level.

 

So what do we know?
The tunnels are about a metre high, the mine 10 metres deep, supported by pillars made of silver birch, which suggests that it was an after-thought, as all good timbers having been used up elsewhere. The metal-bearing vein, which sits on top of a mixture of sandstone and clay is about 10 millimetres thick, just enough ore to be excavated by hand while stooping or crawling through the tunnel.

 

In 1803-1815 Napoleonic wars were raging in Europe, and the French fleet effectively blockaded the English Channel, disrupting imports of cobalt. Unlike today’s battery market that dominates cobalt’s use, the main market then starved of cobalt was pigment, specifically bright blue pigment for English potteries that operated in Derbyshire and Yorkshire.

 

The Alderley Edge land was owned by Sir John Thomas Stanley. After cobalt was discovered there in 1806, and sensing a lucrative market, in 1808, Sir Thomas leased the supply of cobalt ore to Tomlinson, Plowes and Company of the Ferrybridge Pottery, Yorkshire. This agreement appears to have ended after little more than a year, but cobalt ore continued to be mined at Alderley Edge and was processed at Wallasey in north-west England in works operated by the Secombe Cobalt Company.

 

The cobalt mineral, asbolite, was separated from the other minerals as far as possible, treated to make a concentrate, and packed into barrels which were sent to the processing plant where the blue cobalt oxide was produced and manufactured into zoffre and smalt. Zoffre was a fused mixture of cobalt oxide and flint used to impart a blue colour to porcelain. Smalt, pulverised cobalt oxide, silica and potash glass, was used to give paper a blue tint.

 

There is no evidence that any cobalt from the mine ended up in metallurgical use. Unfortunately, some mine documents perished in a fire at one of the residences of the Stanley family.  Among the mine’s secrets is an inscription on its wall ‘WS’ with the date ’20th Aug 1810’. Far from the casual “I woz ‘ere”, the initials are written with a flourish. So who was this WS, a mine manager or estate owner, a rare illustrious visitor, or was it a company brand?

 

We may never know, unless National Trust’s researchers dig up something else new and exciting. After less than a decade of cobalt mining, the Napoleonic War ended, and the navy blockade was lifted. In July 1817, after imports of cobalt from Europe resumed, the business at Alderley Edge was wound up as abruptly as it started. The cobalt mine, hastily abandoned with its equipment left behind, lay undiscovered for more than two centuries.