
%0 Journal Article
%A Kirkman, JH 
%A Pullar, WA 
%T Halloysite in late pleistocene rhyolitic tephra beds near Opotiki, coastal Bay of Plenty, North Island, New Zealand
%J Soil Research
%D 1978/04/01
%V 16
%N 1
%P 1-8
%K 
%R https://doi.org/10.1071/SR9780001
%U https://www.publish.csiro.au/paper/SR9780001 
%X Investigation of the clay mineralogy of 14 rhyolitic tephra beds with a suggested age of 125000 to 220000 years revealed that the squat cylindrical form of halloysite is the dominant crystalline mineral. This mineral has probably crystallized from allophane over a long time period, excess silica being precipitated as a weakly hydrated phase. The squat cylindrical crystals perhaps characterize halloysite formation in rhyolitic tephras. 
