Summary:
Sediments of the Upper Pottsville Mary Lee coal zone are Lower Pennsylvanian in age and are comprised of cyclic sequences that include sandstone, siltstone, shale, and coal. Located within the middle of the Black Warrior Basin stratigraphic sequence, the Mary Lee and Blue Creek horizon is situated below drainage throughout the Property and is accessed by shafts.
- The New Castle seam is present approximately 20 to 80 feet above the Mary Lee seam.
- Lithologic composition of the roof strata varies throughout the Property, consisting primarily of a coarsening-upward sequence of shale or sandy shale, with occasional sandstone channels located within the immediate or main roof of the Mary Lee seam.
- In areas where sandstone occupies the immediate roof of the Mary Lee seam, seam scouring may locally occur. Where sandstone channels are present within 4 to 6 feet above the Mary Lee (roof bolt horizon), there is potential for increased draw rock conditions and roof instability beneath the sandstone/shale contact.
- Thickness and composition of the stratum comprising the Middleman are variable, ranging from shale, carbonaceous shale, or fireclay, to sandy shale.
- Areas where the combined thickness of the Mary Lee – Blue Creek horizon is less than a minimum CM cutting height (7.0 feet) are generally rare, and where this occurs, roof (and/or floor) strata are expected to be excavated as out-of-seam dilution (OSD). Areas where the thickness of the Blue Creek seam is less than a minimum longwall cutting height (5.0 feet), and only the Blue Creek seam is planned to be longwall mined, occur in the Northeast, Far North, and Central areas.
- Compositional variability and thickness of the floor strata of the Blue Creek seam in a fining-upward sequence vary from very soft, thick fireclay within the immediate floor, to sandy fireclay, shale, sandy shale, and finally sandstone within the first three feet below the seam. Fireclay varies in thickness, from less than a foot to more than 10 feet. Due to its inherently high clay content, this stratum is typically moisture-sensitive and may degrade when exposed to water accumulation on the mine floor.
Mineralisation
Regional coal rank in the BWB generally ranges from a low-volatile coal in the southeastern portion of the basin to a high-volatile coal in the northwest. Due to the value of the Mary Lee and Blue Creek seams in the metallurgical coking coal market at the Mine No. 7 operation (and adjoining mines), the subject coal seams have been extensively mined in the region. Laboratory data for the Property on a dry, clean coal (1.50 – 1.55 float) basis indicates a typically low- to medium-volatile bituminous coal product. The utilization of two longwall mining units allows Warrior to sequence the mine plan at Mine No. 7 to produce a consistent volatile product.