This study of the mode of occurrence and distribution of selenium in a rock core from southcentral West Virginia reveals that total selenium concentration varies by rock type. Rocks with total selenium \u3e1 mg/kg were of circum-neutral pH based on acid base accounting data. No direct correlation was found between selenium concentration in the rocks and that of sulfur and/or total organic carbon. The distribution of total selenium was also controlled by stratigraphy. The amount of total selenium extracted from various rock types like coal, shale, sandstone, mudstone and carbolith materials ranged from 50%. Selenium extracted from coal was mostly from the sulfide fraction. Selenium extracted from shales averages approximately 40% by mass, mainly in the organic fraction. More selenium was extracted from shales in coal-proximate zones averaging about 50% by mass. Extraction conditions are rarely encountered in natural geochemical settings and are thus likely an overestimate of field conditions
