Johnnies Reward Prospect (Johnny's), Pinnacles Bore Copper Area, Strangways Range, Central Desert Region, Northern Territory, Australiai

Regional Level Types
Johnnies Reward Prospect (Johnny's)	Prospect
Pinnacles Bore Copper Area	Area
Strangways Range	Mountain Range
Central Desert Region	Region
Northern Territory	Territory
Australia	Country

Located one kilometre north-east of the Southern Cross bore.

Dismissed by BMR as un-economic, however it did not stop a succession of explorers taking over the lease, and making wild claims. Soon after each annual report, the lease was sold. Discovered 1964. Explorers include Geopeko, Magellan Petroleum, McMahon, Flinders Diamonds Ltd, Teck Cominco-BHP Billiton, Alcoa, Maximus Resources, Davenport Resources, Transol, Arunta Resources until 2013. Various descriptions for the deposit exist, some at conflict with each other. The below has been chosen as the most comprehensive.

Country rock biotite-garnet-quartz gneiss. The lode outcrops as four prominent exposures along a north-south length of 180 metres of amphibolite-gneiss, enclosed by quartzite and magnetite rich lenses, dipping 65 degrees east, steepening to vertical in the eastern side. There is a very small pyroxenite body enclosed by the lode, containing rare pseudomorph limonite after pyrite, and chalcopyrite.

The amphibolite is pale-brown aggregates of parallel fibres, or unweathered as pale green to colourless, acicular crystals. Asbestos veinlets cut the amphibolite in the most prominent outcroppings. The amphibolite-gneiss is cut by thin lenses of garnet-biotite gneiss, being localised calcareous at the margins, with magnesite float.

The lode consists of tremolite-actinolite-magnetite rock, with calcite-actinolite margins. The lode contains disseminated chalcopyrite associated with magnetite as irregular patches, but consisting of 30% volume of the lode, and pyrite, rare galena and molybdenite. Also sparsely disseminated malachite, and uncommon white smithsonite coating fractures along the main part of the lode. Two thin layers of quartzite and garnet-biotite gneiss occur in the lode, cut by calcite stringers.

Grade at the surface is up to 0.34% Cu, 0.17% Pb and 0.13% Zn. No gold is found at the surface, but in the core of the lode grades up to 0.49 dwt Au.

Other Regions, Features and Areas containing this locality

References