Whitianga Quarry, Whitianga, Coromandel peninsula, Thames-Coromandel District, Waikato Region, New Zealandi

Regional Level Types
Whitianga Quarry	Quarry
Whitianga	- not defined -
Coromandel peninsula	Peninsula
Thames-Coromandel District	District
Waikato Region	Region
New Zealand	Country

Road metal quarry, altered andesite of early to mid-Miocene age.

The sequence showing in the quarry is a basal andesitic lava and agglomerate, followed by 20-25 metre thick andesite clasts and metasedimentary rock layer in hydrothermally altered ash. This is overlain by another andesite lava flow, up to 20 metres thick, then a second layer of agglomerate 2-3 metres thick, and finally an uppermost 10-15 metre thick andesitic lava layer.

Of interest was the discovery of lanthanite (Nd) in the quarry as lustrous glassy vivid pink thin bladed crystals to one millimetre, and rarer vivid pink blocky equant crystals. The lanthanite was found in a small section of the quarry, the bright pink colour caused by its high Nd content. The crystals are found in solution cavities in highly altered fine grained grey-green feldspathic crystal tuff. At the time of writing lanthanite (Nd) was recorded on Mindat at only nine other locations worldwide.

Also found in the quarry is fine grained pyrite in joint and fracture linings, showing as minute cubic and framboidal forms, with some flattened discoidal or prismatic siderite. Common clinoptilolite, often associated with the lanthanite, and along joint planes as stalactitic aggregates of colourless to pale yellow tabular crystals. The eastern edge of the quarry contains abundant calcite, with minor aragonite.

A visit in Feb 2019 found limited working of exposures and the material being worked is very tight with few voids for mineralisation. Material found on this visit was all in older material scattered on the quarry floor and much of this was badly weathered. It is unlikely that any future collecting would be productive.

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