Tihiroa Coalfield : An Assesssment of Coal Resources Survey Exploration, 1979-1984

Tihiroa Coalfield was discovered by exploratory drilling east of the known Kiwi field, South Waikato Coal Region, undertaken as part of the Coal Resources Survey funded by Mines Division, Ministry of Energy. Sixty nine holes were drilled between 1979 and the end of 1984. Additional seismic gravity and magnetic surveys were made in conjunction with the drilling programme. Tihiroa coalfield is located about 40km south-west of Hamilton, immediately west of the Waipa river between Pirongia Mountain and Otorohanga. Volcanic flows and breccia underlie the north of the area, mostly supporting a gentle topography, though steep sided valleys have been cut on the southern flanks of Pirongia Mountain, and small volcanic vents occur at Mokootipi and Turitea. So far, coal of mineable thickness is known only at depths greater than 100m and most is between 200 and 400m. Shallow coal in the south-east Ongaruhe Sector has not been found in significant quantities.