Mineral Claim 84 Cu deposit (Anticline prospect), Ashburton Downs Station, Ashburton Shire, Western Australia, Australiai

Regional Level Types
Mineral Claim 84 Cu deposit (Anticline prospect)	Deposit
Ashburton Downs Station	- not defined -
Ashburton Shire	Shire
Western Australia	State
Australia	Country

11.4 km WSW of Ashburton Downs Homestead. Approximately 500 metres east of the Bali Lo deposit.

Type locality for Ashburtonite, which occurs here as clusters of clear blue, prismatic crystals up to 0.4mm long. Associated species with ashburtonite include diaboleite, duftite, beudantite, caledonite, plattnerite, cerussite, malachite and brochantite. Ashburtonite was discovered by Blair Gartrell (along with gartrellite) in 1989.

The Anticline prospect is also the type locality for gartrellite, which occurs as soft yellow to greenish yellow powder.

During four trips between 1985-1990, Blair Gartrell collected 2000-3000 specimens from the area, the majority from the Anticline prospect. Many are in the CSIRO and Western Australian Museum collections. Those in private hands are likely from Blair's personal collection, named the Westaus Mineral Museum in Beverley Western Australia, the specimens sold in the mid 1990's after Blair's death. Most specimens are seen from nearby Bali Lo, or at least they are labelled as such.

The deposit was discovered by Westfield Mining in 1963 while exploring the area. The company excavated a 29 metre deep inclined shaft, a crosscut, short drives and several shallow diggings. Minerals encountered in the shaft were disseminated pyrite, galena, chalcopyrite, bornite, digenite, covellite, tetrahedrite, skutterudite and a Cu-Sb Sulphide.

The site has an assemblage of secondary minerals in a weathered shear zone that cuts a series of shales and greywackes. These secondary minerals are derived from a primary sulphide assemblage including chalcopyrite and galena. The secondary assemblage are largely hydrated carbonates, arsenates and sulphates of Pb and Cu, and to a much lesser extent Zn and Fe.

The deposit sits on a west north-west trending anticlinal structure, along a sheared fault zone, near the contact of the Capricorn and Ashburton sediments. The average width of the mineralised zone at the Anticline prospect is 1 metre, varying from 30cms to 2.5 metres. The shear zone is marked by white alunitic clay, relict irregular banding, and abundant secondary ore minerals. Some parts are compact and massive, but other areas porous, friable, with frequent vuggy cavities in which secondary mineral crystals are found. This prospect shows an abundance of minerals from the alunite-beudantite-crandallite group.

No mention is made of the tennantite boxwork found at Bali Lo. The Bali Lo minerals are said to be more coarsely crystalline, but otherwise share similar characteristics between the two deposits.

The 1993 reference mentions three un-identified species: PbAl3(SO4)2(OH)6? in the Sulfates class, and Cu,Ca,Na,Cl,P,As in the Arsenates and Sulfarsenates class, and Ag,Hg,Cl,S in the Halides class.

Other Regions, Features and Areas containing this locality

References