Gladstone Hill Mine (Waihi Gladstone), Waihi, Hauraki District, Waikato Region, New Zealandi

Regional Level Types
Gladstone Hill Mine (Waihi Gladstone)	Mine
Waihi	Town
Hauraki District	District
Waikato Region	Region
New Zealand	Country

Gold-silver.

Silicified caps, quartz veins and hydrothermal breccias in andesite.
An hydrothermal eruption occurred in vent structure. Vent breccias are overlain by an eruption breccia tuff ring and by carbonaceous sediments that filled the eruption crater.
Three stages of alteration :
- Calcite-chlorite-smectite (early stage)
- Adularia-quartz-illite (early stage)
- Illite-smectite-kaolinite-pyrite (late stage)

The Gladstone Hill site is immediately west of the present Waihi Mine processing plant, 2 kilometres east of Waihi. It was the location of minor historic mining, and recent exploration. The veins occupy the far southern section of what is now called the Favona vein system.

The earliest reference found was 1889, when the mine was owned and operated by William Brooks, employing about six men. The lease was forfeited to Henry Brett in 1891. Much development work then was undertaken, under the supervision of F. Hollis. The lease, together with the Salisbury, and Joker claims were floated in London in 1895 with £15,000 working capital. Little appears to have come of this and the lease by 1901 is in the name of Henry Gilfillan, who works it until at least 1911.

The veins contain erratic Au-Ag mineralisation, with local rich sections up to 150 g/t Ag, and 63.5 g/t Au, but most of the deposit is uneconomic. The total mined historically is 502 tonnes of quartz, yielding 761.6 ounces of gold.

The host is Miocene aged pyroxene andesites, containing phenocrysts of plagioclase, hypersthene, and augite, overlain by the Black Hill hornblende and biotite bearing dacite.

The veins are vertical to steep south-east dipping, and trending north north-east. The veins range in composition from chalcedonic, crudely banded, to quartz replacing calcite, some white clay filling voids and coating fractures, and brecciated. Acid sulphate alteration is best expressed in the brecciated areas.

Quartz-calcite comes in a variety of forms including platy calcite, massive calcite, and quartz as colloform, crustiform banding, lattice bladed, zonal, comb, massive and feathery. The crustiform banded is the dominant form, containing variable Au-Ag grades. Feathery forms in breccia, and colloform also contains mineralisation.

Pyrite veins were the first to form and are common in the deposit. Base metal sulphides increase at depth, containing Au-Ag associated with pyrite, sphalerite, galena, marcasite, and rare chalcopyrite.

Other Regions, Features and Areas containing this locality

References