It must tie added, however, that the surface waste heaps which have been the mainstay of the Derbyshire output for the last six years have now been well picked over and are no longer of serious account for future supplies. Bulletin - Page 1561927Full view - About this book
| United States. Bureau of Mines - 1919 - 1164 pages
...added, however, that the surface waste heaps which have boon the mainstay of the Derbyshire output f»r the last six years have now been well picked over and are no longer of serious account for future supplies. Cornwall. — "So fluorspar is being raised in Cornwall, but... | |
| United States. Bureau of Mines - 1919 - 1184 pages
...of a greatly Increased annual output for a great number of years.1 It must tie added, however, that the surface waste heaps which have been the mainstay...years have now been well picked over and are no longer of serious account for future supplies. Cormcall. — No fluorspar is being raised In Cornwall, but... | |
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