Zeolites from a new locality at Ben Lomond, New England Region, New South Wales
Abstract
A roadside quarry on the New England Highway near Ben Lomond in the New England Region of New South Wales has revealed an interesting association of zeolites and other secondary minerals lining vesicles in Tertiary basalt. The zeolites present (chabazite, phillipsite and natrolite) are those characteristic of a silica-undersaturated (alkaline) environment. Associated secondary minerals include radiate globular saponite, calcite and aragonite. The calcite is present in a number of different habits, each showing a different response to ultraviolet light and the aragonite also shows a diverse range in morphology. Zonal distribution of the zeolite species is pronounced with the zoning centred around what appear to have been hydrothermal spring conduits. Two distinct episodes of mineralisation are evident, an early deuteric suite formed during initial cooling of the basalt and a later suite (including chabazite and radiate globular saponite) deposited by a further influx of hydrothermal fluids associated with subsequent proximal hot spring activity. The basalt at this locality has undergone extensive hydrothermal alteration.
