What kind of rock is this?

It was found in Threemilestone, near Truro in Cornwall, UK. The rock has a hardness of over 5.5, as a knife doesn't scratch most parts of it. It is 10cm across the top, and 13cm across, from the top left to bottom right.

I would like an expert to analyze this please.

Picture 1 Picture 2

  • 3
    $\begingroup$ You should follow the recommendations in meta.earthscience.stackexchange.com/questions/124/…. $\endgroup$ – arkaia Jul 22 '15 at 19:53
  • $\begingroup$ If your original photos are higher resolution, could you put those directly into your post rather than the screenshot of the two images? $\endgroup$ – casey Jul 24 '15 at 1:24

Looks like a epidote bearing skarn or tactite. Cornwall England is famous for tin and copper bearing skarns. Epidote is a common gangue mineral in these types of deposits.

Skarns are typically formed at the contact zone between intrusions of granitic intrusion and carbonate sedimentary rocks such as limestone and dolostone.

Decent summary of skarns can found at: https://en.wikipedia.org/wiki/Skarn


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