Great Flat Lode exotic semiconductor field trip

The Great Flat Lode is the name given to a huge vein of ore that extends for several miles underneath the area of Carnkie, south east of Camborne. Unlike most lodes in Cornwall that are more or less vertical, this one is more parallel with the surface and only increases in depth slowly. This is also the of modern mining, as recent developments at South Crofty mine (one of the last to close, in the early 90s) hope to reach a potential parallel tin lode some distance underneath the great flat lode in the next few years.

I didn't have any particular semiconducting minerals I was searching for on this trip, it was more about learning about the nature of the rock formation here. The geology is quite different to the mines further to the east I'm more used to - some of the mines here extend deeper into the earth, and the temperature and chemistry resulted in different assemblages of minerals to form. A big difference is that most of the mineralisation seem to be formed in granite rather than the killas (judging from the rock I found on the dumps). Also from these observations there seems to be much less arsenopyrite and pyrite, less iron in general (and where it does occur more likely as hematite). Miners and balmaidens moving around Cornwall must have been very aware of these differences, it's quite disorientating.

One theory I want to test is do these differences result in different using semiconductors from here?

There are also more radioactive minerals present, so I took a bit more notice of the Geiger counter. There also seem to be less recent and still exposed mine dumps here, so I wasn't sure which sites would be overgrown or even accessible, let alone if I could find anything.

South Condurrow Mine

I started to the west of the great flat lode, at Condurrow (Marshall's shaft). This site is very overgrown, but I found a path in to the engine house and a small network of paths leading on, one heading to a small area of exposed rocks falling out of the side of a dump as it weathers away.

It took a bit of time here to find anything, and I didn't find much in quantity - but it more than made up for it in quality.

East Wheal Grenville

The second site was only a short distance away, at one point part of the same amalgamated mine. However after a walk around the site it appeared to be entirely overgrown with the only surface rocks visible in the tracks here and there. It's possible there may have been some in under the tall bracken - but difficult to tell at this time of year.