Industrial Minerals in New Zealand
Bentonite Bentonite is mined by Omya (New Zealand) Limited in the Harper Hills near Coalgate, 65 km west of Christchurch (Fig. 2). Annual production peaked at 19,722 t in 1970, and was 7,000 t in 1996. Nonswelling calcium bentonite occurs in a main bed up to 62 m thick, separated from a lower, carbonaceous bentonite bed by 3 to 4 m of quartz
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