Table 1: Coal seam roof and floor lithology and the characteristics of efflorescent-oxidised rock mass.

ClassificationLithologyThickness (m)Characteristics of efflorescent-oxidised rock massRQD (%)Drill core photographs

Main roofGritstone10.6Faint yellow colour, weak lustre, fractured, loose structure45.4–56.7
Immediate roofMudstone1.48Weak lustre, water-swelling clays, fractured, high level of efflorescent oxidation in clay5.2–18.5
Number 9 coalCoal9Soil lustre, sepia, water-swelling clay, high level of efflorescent oxidisation in clay0
Immediate floorMedium sandstone2.3Faint yellow colour, weak lustre, fractured, unconsolidated structure45.4–56.7
Main floorMudstone2.7Sepia, soil lustre, fractured, unconsolidated structure5.2–18.5