Doole, M.H.; Christie, A.B.; Brown, L.J. 1987 Sheet QM361 Grassmere : geological resource map of New Zealand 1:250,000. Wellington: DSIR. New Zealand Geological Survey report M 154. 23 p.
Abstract: Aggregate, salt and limstone are produced in Sheet QM361 Grassmere. Aggregate is obtained from the major rivers and their tributaries, and used locally for river protection (riprap), roading, an ballast. Limestone is quarried for local use as aggregate and in agriculture. New Zealand's only solar salt works is sited at Lake Grassmere. All three major commodities are in plentiful supply for future use at their present rate of extraction, and there is potential for expanding the salt operation. Oil and gas seeps occur, but no detailed prospecting for petroleum has been carried out. Bentonite occurs at Kekerengu, but is of inferior grade to occurrences in the North Island and in Canterbury. Minor disseminated copper and nickel mineralisation occurs in ultramafic rocks at Blue Mountain