Petrography of the coal from the Oranovo–Simitli basin, Bulgaria and indices of the coal facies

Abstract

Petrographic analyses of 137 Bulgarian coal samples collected from an underground mine in the Oranovo–Simitli basin show vitrinite (huminite) reflectance values near 0.34%. This middle Miocene age coal is mostly made of vitrinite (huminite), with about 10% liptinite and lesser amounts of inertinite. The inertinite group macerals are entirely funginite (sclerotinite) and inertodetrinite. The liptinite group macerals include fluorinite, which is identified for the first time in a Bulgarian coal. The abundant, degraded vitrinite group macerals result in a high gelification index and a high tissue preservation index, which are consistent with a forested, continuously wet raised-bog depositional environment.