Marshall Attutra, Jervois Range, Jervois Station, Central Desert Region, Northern Territory, Australiai

Regional Level Types
Marshall Attutra	- not defined -
Jervois Range	Mountain Range
Jervois Station	- not defined -
Central Desert Region	Region
Northern Territory	Territory
Australia	Country

Marshall Attutra are two parallel north-south trending lodes, 15 kilometres north of the Plenty Highway, 500 metres west of the Lucy Creek track, as part of a J shaped steeply north plunging syncline, 2 kilometres east of the Jervois Range escarpment. The lodes occupy a ridge immediately south of Unca Creek, with Hanlon's Reward mine 500 metres north, and the Green Parrot mine 500 metres south. A derelict processing plant is just west of the mine.

(Wygralak) states in summary the Marshall Attutra deposits are closely spaced Cu-Pb-scheelite ore bodies, hosted by magnetite-quartz, calc-silicate rock, and skarn. The mineralised zone is below quartz-muscovite, and spotty andalusite zones in Bonya Schist. The lodes are tabular, and steep dipping towards the syncline axis, trending north-south.

(Robertson) From west to east at the deposit is quartz mica schist, then a 50 foot thick porphyroblastic cordierite-quartz-muscovite schist, then 40 foot thick quartz-mica schist again, next the magnetite-garnet-quartz granulite lens containing the Marshall lode 460 feet long. The southern part of this is cupriferous.

The Attutra lode is separated by 200 feet of quartz-mica schist, the schist containing no copper apart from a small biotite enriched lens to the south-east. Within the schist unit is a band of cordierite porphyroblasts, adjacent to the lode, with an irregular and shattered contact. The eastern part of the Attutra lens is up to 70 feet wide, containing schistose garnet-biotite-quartz granulite. The western part of the lens is up to 10 feet wide, containing grossularite-vesuvianite skarn rock, then another 10 feet of quartz-mica schist to another lens up to 50 feet wide of quartz-garnetite. This grades west into an irregular lens of garnetiferous epidosite up to 40 feet wide, then rubbly outcrops of porphyroblastic cordierite-quartz-mica schist.

Copper is found in the epidosite, garnetite, skarn and granulite, with particular concentrations in the centre part of the garnetite, and lesser so in the granulite. Copper is richest in zones of shearing, and in the Marshall lode, copper is confined to partly sheared magnetite-garnet-quartz granulite, near the boundary, and partly within the schist to the east.

The deposit contains a shaft down to 92 feet showing weak mineralisation, and a couple of open cuts to the north, with a concentration of bismuth. Chalcopyrite and pyrite crystals are disseminated in granulite, quartz, and magnetite-quartz rock. There is also some bornite and pyrrhotite. Sulphides in the lead lodes is galena and sphalerite. Scheelite is found at the mine at the contact between mica schist and epidote rich calc-silicate rock, as disseminated scheelite along a length of 1800 feet,6 inches to 2 feet wide.
Scheelite is also found in a discontinuous quartz-epidote horizon up to 2 metres wide, up to 2 kilometres east of the Marshall Attutra, and Green Parrot mines. It is parallel to the J structure, with sporadic quartz-magnetite outcrops. Around 5 kilometres south-west of the mines are several scheelite deposits in calc-silicate rock, some being also plugs of vesuvianite up to 20 metres across.

Robertson states the crystals of chalcopyrite and pyrite at Marshall Attutra
have an unusual form without elaborating. The lodes are truncated to the north, marked by the Unca Creek. Small quartz blows up to 50 feet long, and quartz-mica pegmatites are common in the area surrounding the mine.

Attutra is a local aboriginal name for the area meaning 'place where parrots get their green'. European discovery was by cattle drover Tom Hanlon in 1929. T.B. Crosbie held the lease from 13 August 1945 to 23 August 1950, until it was forfeited for non-compliance of labour conditions. Then K.G. Johannsen held the lease from 25 September 1949 to 29 October 1971. He intermittently mined several deposits in the area during the 1950's and 60's, carting ore to Mount Isa for flux, and erecting two concentration plants to produce material for the fertilizer industry.

New Consolidated Goldfields explored the area from 1961-1965, then Petrocarb Exploration NL in the early 1970's. The Plenty River Mining Company took out 2000 tonnes of ore from the Marshall Attutra and Green Parrot mines from 1981 to 1983, when low metal prices forced them to abandon the project. Otter Exploration explored the area in the late 1980's. At the time of writing KGL Resources had held the leases for several years.

Other Regions, Features and Areas containing this locality

References