£1.00 – £1.90
Bituminous coal is a soft sedimentary rock with a high organic content & the tar-like substance Bitumen. It is of a lower grade than Anthracite but higher grade than Lignite.
Bituminous coal is an organic sedimentary rock formed by diagenetic and sub metamorphic compression of peat bog & swamp material. Its primary constituents are macerals: vitrinite, and liptinite. The carbon content of bituminous coal is around 60-80%; the rest is composed of residual water, air, hydrogen, and sulphur. It is graded according to its vitrinite reflectance, volatiles content, plasticity & ash content which in turn gave rise to specific uses e.g. smithing, coking or just general heating fuel. These particular examples are from the Carboniferous deposits in Yorkshire. Specimens are supplied in labelled card trays.