"Knockers" in Welsh Lead Mines: A Geological Explanation?

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Overview:

Title: "Knockers" in Welsh Lead Mines: A Geological Explanation?
Author: R. S. Pyne
Year: 2008
Type: Essays

Editions/Publications:

Unknown. NewMyths.Com, September 2008 (Unknown, R. S. Pyne, NewMyths Publishing, $0.00, webzine, MAGAZINE)