 ... coating, which is probably due to the alteration of the weathered coal. The chief impurities of the coal are sulphur balls and small lenses of pyrite that are scattered somewhat irregularly through the bed. The higher coals are also distinctly black,...  Bulletin of the United States Geological Survey - Page 130by Geological Survey (U.S.) - 1910Full view - About this book
 | Geology, Economic - 1909 - 504 pages
...is no doubt due to th.e alteration of the weathered coal. The chief impurities of the coal are the sulphur balls and small lenses of pyrite that are...from the mine. They show more traces of iron stain and contain considerable gypsum and salt flakes in the joints or bedding planes. On exposure to the... | |
 | United States - 1909 - 520 pages
...which is no doubt due to the alteration of the weathered coal. The chief impurities of the coal are the sulphur balls and small lenses of pyrite that are...from the mine. They show more traces of iron stain and contain considerable gypsum and salt flakes in the joints or bedding planes. On exposure to the... | |
 | Marius Robinson Campbell - Coal - 1910 - 616 pages
...shipping without breaking down. On burning it produces no clinker and leaves a small bulk of red- white or reddish ash. Samples taken from surface prospects...more traces of iron stain than the Rock Springs coal and contain considerable gypsum and salt flakes in the joints or bedding planes. On exposure to the... | |
 | Coal - 1910 - 216 pages
...alteration of the weathered coal The chief impurities of the coal are sulphur balls and small lens -of pyrite that are scattered somewhat irregularly...from the mine. They show more traces of iron stain thai the Rock Springs coal and contain considerable gypsum and salt flakes, in the joints or bedding... | |
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