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. (C) 2003 Published by Elsevier B.V.