Tindale Spelter and Fume Works

 We were unable to locate the Black Redstart but we did learn something about brass.

The mining activities in the district produced quantities of zinc ore. By the nineteenth century it was possible to extract zinc in the UK and combine it with copper to make brass. The works that did this were in the hole shown and were called the spelter works.

The concrete buildings on the top were twentieth century fume works where waste material from the spoil heaps was vaporised to allow the zinc to be extracted.

My source for the information is here.