Watching rocks melt

In the southwest you can hardly walk a mile without bumping into an old chimney belonging to some mine. Quite often a tin mine. The dumps with mine waste are still there, the rivers are full of alluvial ore, and there’s many people around still who have in the past earned their living with it. And some people keep the dream alive. One of these people is Neil.

A whole bunch of tin nutters would gather somewhere near Truro to smelt a lot of the ore they would have gathered and crushed over the months. And I tagged along. Smelting needs a photographer!

We arrived the night before, and were greeted warmly by Bernie, the host. It’s his furnace on his land that would be used. But not yet! The evening was for wine, food, catching up, and watching a DVD with footage of Levant mine. And then bed early; the next day would be a tough one!

The plan was that the men would smelt for at least 12 hours, and I don’t stay fascinated with such for that long, so I had brought all sorts of things along. My first priority was trying to fix my old waterproof camera. I’ll report on that later! I also brought my laptop, three books, a set of articles, running kit, and some more to keep me busy. Before the furnace was hot for the first time I was done with my camera.

Neil does some last ore or anthracite crushing

Through the hole in the furnace you can see the red hot crucible with the glowing froth. Pic by Neil

When the ore is molten it can do with some stirring... 

 The frothy melt is quite viscous

Looking down the furnace can make you look like this...

The furnace takes a crucible with about a kilo of ore and anthracite. A flame fed by an enormous gas bottle heats the whole thing up until the ore mix is a bright orange, radiant, frothing boiling mass. When the frothing recedes the tin crucible can be taken out, and the tin poured. It’s very photogenic!

First the tin comes out...

...and then the slag...

...which is very photogenic...

...QED! (Pic by Neil, evidently)

One then has to separate the tin from the slag, which involves some hammering.

The tin is then re-melted in a ladle in the flame above the furnace.

This picture proves I was really there! Pic by Neil

The slagless tin can then be cast into ingots

Every crucible fill needs about an hour, so there’s a lot of dead time involved. In between smelts (which I was good at missing) I got blogging, data editing, book reading and all sorts done. Very useful. At some point I even went for a 1.5 hour run. That turned out to be a bit of an obstacle course with stepping stones, dense vegetation, clamorous peacocks, disappearing engine houses and appearing reservoirs, loud dogs, cute dogs, confusing road signs and English/Cornish confusion, but it was a good run!

At the height of the day there were ten people; among them even the former exploration geologist of Geevor mine. I was a bit humbled! But they were all lovely people. But when I got back from my run it was only Bernie, his wife Julia, Neil and me. And the men smelted on into the evening, getting more and more bold in doing so. Normally one would only smelt crushed ore; that way you can get all impurities out. But in the end they were smelting inch-sized beach pebbles with ore in them. And got away with it! So yes, some may spend their Saturday watching paint dry, or watching grass grow, but I was watching rocks melt. Meanwhile the pictures got better and better with the fading light; a red hot crucible is best after dusk!

Can you melt entire pebbles in such a furnace? Pic by Neil

Yes you can...

And even bigger ones! Pic by Neil

But your slag gets very silicic.

And then the sun set!

A glowing crucible is prettier after sunset.

It looks positively menacing if you ask me.

This picture was taken without using the zoom. Not necessarily good for your camera...

After the last smelt everybody was tired, and we ended the day with showers and drinks. A successful day! The men had smelted more than 3 kilos of tin... who would have thought that AD 2011!

Neil and Bernie proudly present the ingots. This even isn't all of it; notice the picture was taken when the sun hadn't set yet!