Evaluation of the Optical Properties of Some Coal Types

Three sets of Carboniferous coal samples taken from north-eastern England and Scottish Fife were subjected to reflected light oil immersion techniques in an attempt to characterize and differentiate their optical properties.

Although the character of the coals varies remarkably, they are separable into two distinct groups based on rank values. The higher rank values attained by both the South Northumberland and the Howick – fault samples are attributable to thermal influence experienced by these coals due to the Alston block and Whin Sill/dyke respectively. On the other hand, the lower rank values manifested in the Westfield is a reflection of both clean/homogeneous surface and the heavy bitumen staining of the vitrinite particles.

The overall form and type of the maceral groups and their relative distribution in Northumberland and Howick are suggestive of similar deltaic environment of deposition. The Westfield, in contrast, is characterized by the relatively high proportion of alginite macerals believed to be preserved under lacustrine conditions.