Our PBS station has begun a “Masterpiece” series called Poldark set in Cornwall. In the second episode, Poldark tries to revive the family tin mine, “Wheel Liesure.” It caught my attention because we had been in “Wheel Mexico.”
Alie was looking at a list of attractions when we were in Cornwall and said “let’s visit a tin mine.” Cornwall’s economy in the 18th and 19th centuries was based on tin.
Around 4000 years ago, people in several places in Europe discovered combining tin and copper produced an alloy, bronze. The ‘Stone Age” was over. Cornwall was one of the rare places that had both tin and copper. Copper can be found naturally, but tin has to be dug out and smelted. I still wonder how they discovered that.
The first tin was found in stream beds where the natural action of the water broke down the rock and washed away sulfide contaminants; the tin concentrate was smelted using charcoal. Ore was obtained from streams as late as the 20th century.
Early mining was probably just digging a pit following a lode. By the 16th century, water in the mines was a problem, so they dug an adit, a slightly dipping shaft that drained the water to the sea. Ideally the adit would also have lodes of ore.
Cornwall lodes were narrow and almost vertical. So horizontal shafts were dug, and then the exposed lodes were followed – often for hundreds of feet – up from the shaft. The miners dug and blasted above their heads working from ladders and temporary scaffolding. The shafts were called stopes and the process, stoping. The ore was carried along the horizontal adits to be hauled out to the surface through the main shaft.
In 2006, UNESCO recognized the Cornwall and West Devon Mining Area as a World Heritage Site. The St. Just Mining District in western Cornwall is part of this site and includes the Botallack, Levant and Geevor mines. We vsited the Geevor Tin Mine. The mine closed in April 1986 and is now preserved by a non-profit charitable organization.
One must wear a hard hat everywhere on the property. We visited the compressor house and the “Dry,” saw the “Victory Shaft,” went through the mill and took an underground tour of Wheel Mexico. Of course there was also a museum, cafe and souvenir shop.
The main vertical shaft was the 1919 Victory Shaft, 1575 feet deep. The shaft had three distinct spaces, two with “elevators” to haul ore and people and one with a ladder for service. The service part also had compressed air pipes, electric cables and a pipe to bring out water from the pumps.
A “cage” could hold 9 men. The ore was brought up in two ton “skips.” Pumping stopped in 1991, and water filled the mine to three hundred feet below the surface. At that point an adit drains it into the sea.
We saw a 1923 steam-powered horizontal winder which pulled up the cages and skips. It is the larger of only two left in Cornwall. After the mid-1950s, it was only used when ropes were being changed on the electrical winder although the steam winder was actually faster.
Mine rescue equipment had a tank of air and chemical re-breathers to absorb carbon dioxide. They were good for up to two hours, but the rescuers couldn’t talk, so they used horn signals to direct operations.
In the mill, a picking belt was originally used to hand-pick out pieces of rock that had no ore; this process was eventually up-graded to a system in which the rock floated on a dense liquid, but the belt continued to be used to clean out scraps such as nails, timber, wire and broken tools mixed in with the ore.
The cassiterite – tin ore – is in fine grains in the rock. Washing and crushing mills reduced the rock to fist sized pieces and then to gravel and then to sand. The ever richer ore was separated as the process continued. Original stamping mills were replaced in 1937 with ball mills, rotating cylinders filled with iron balls that broke up the rock. The ore was then fed into a dense slurry in the heavy media separators where the heavy metal-rich ore sank while the other rock floated and was skimmed off.
The “Dry” was a place where the men could change out of their wet dirty mining clothes before they went home. Steam pipes covered with wood slats ran between the lockers so men could hang their clothes to dry. Quite often, the Dry was also the only place the miners could wait before or after their shift, sheltered from the blowing wet climate outside. In 1986, the time of the closure of the mine, it was still the law that women were not permitted in the mine or on the mine site after dark or on a Sunday. The Dry was a blue collar “men’s club.”
After amusing ourselves panning for gold in an waiting area at the end of the mill, we walked through part of the Wheel Mexico mine which dates from the 18th century. “Wheel” comes from a Cornish word for place of work. No one knows where “Mexico” came from. People were smaller, so the mine is low and narrow. They gave us long coats to protect our clothing from the red mud and dirt. We wore hard hats and ducked, but we still frequently struck our hats on the ceiling. It was hard to imagine that children worked in these mines. I did not notice any children working in Poldark.
Click on photos to enlarge.