Brown, I.R. 1984 Mokau Coalfield: geotechnical evaluation to assist preliminary mining assessment. Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report EG 382 21 p.
Abstract: Geotechnical evaluation of the Mokau coalfield in north Taranaki was carried out in conjunction with coal resource evaluation. Up to six thin coal seams are recognised in the coalfield. Most of the seams could be excavated by opencast methods in areas where dip slopes have formed and there is thin overburden. Areas of steep slopes and thick cover might be mined by underground methods where the seams are thickest. Drill core from about the coal seams has been tested, and apart from a few very well cemented samples, strengths were in the range of very weak to weak. Some of the coal measure rocks had low slake durability, and low angle shear zones may also cause difficulty during mining. Fault throw and spacing, especially for minor faults, is likely to be the most important constraint on underground mine development. As yet, little is known about such structures.