BENTONITE IN CLAY

Press, Volume LXXXIII, Issue 25305, 3 October 1947, Page 6

BENTONITE IN CLAY

DEPOSITS IN SOUTH ISLAND

POSSIBLE ECONOMIC VALUE

Clay slips which caused trouble during the construction of the South Island Main Trunk railway may eventually become the source of a- nonmetallic mineral of value to industry both in New Zealand and overseas. The clay of the notorious Blue Slip, north of Kaikoura, and'’other slips in Marlborough, contain substantial amounts of beqtonite, which, because of its colloidal properties, has many and varied industrial uses, particularly in the United States.

Field work by officers of the Geological Survey has shown that bentonitic material is of widespread occurrence in Marlborough and North Canterbury, and it is possible that a deposit of edßnomic value may be located eventually. Last year bentonites were mapped and reported oh at Blue Slip, Kekerangu, and, Clarence, and more were sampled at Oaro and Waipara. Bentonite is sold in its raw, sundried, and pulverised state. It can be used for foundry moulding, insecticide, cement filling, the manufacture of wallboard, and a multiplicity of other purposes. So far the only production in New Zealand has been from deposits at Porangahau, in Hawke’s Bay, which have been worked on a small scale for several years. The main use has been in the regeneration of moulding sands, and in 1942 quantities were used by an American company searching for oil. Production in the North Island has not been more than 200 or UOO terns a year, and last year only 15,4 tons worth £777 were produced. Inquiries and orders have been numerous both in New Zealand and overseas, but no market of importance is expected until a dryer is provided, and this work is now in hand at Porangahau. The overseas demand for bentonite is expected to increase in the future.