Yinnietharra Dravite North mine, Tomkap tourmaline mines (Soklich), Yinnietharra, Upper Gascoyne Shire, Western Australia, Australiai

Regional Level Types
Yinnietharra Dravite North mine	Mine
Tomkap tourmaline mines (Soklich)	Group of Mines
Yinnietharra	Station (farming)
Upper Gascoyne Shire	Shire
Western Australia	State
Australia	Country

A well-known locality for very large and well-formed dark brown to black dravite crystals. (Reports of "povondraite" from here are unsubstantiated, and all tested to date have been black ferroan dravite). The deposit was discovered in 1918. In 1968 A. Soklich claimed the mining lease and started mining for specimens. During the first period of mining (January 1969 to January 1971) more than 12 tons of dravite crystals were produced. More recently (2010) the mineral lease has been taken up by Tom Kapitany, who renamed it Tomkap tourmaline mine, produced a large amount of specimen material and and provided some of the following information.

It consists on two pits 1km apart roughly parallel and strike north-north west. Brown dravite occurs at the south pit, and black dravite in the north pit.

The dravite is found in a phlogopite-plagioclase schist on Morrissey Hill in the Gascoyne Province of the Precambrian Shield of Western Australia (Bridge et al., 1977). Associated pegmatites cut across the strike of the tourmaline-bearing schists. Regional metamorphosis and deformation of Mg-rich metasediments with highly hydrothermally altered zones allowed tourmaline crystals to form in the mica schists. Dravite rarely has associated fluorapatite crystals up to 125mm. Dravite crystals are mostly stubby and double terminated "floaters", and crystals up to 7kg have been found. There are different zones existing, with 2 contact zones producing smaller crystals and central zone producing giant black dravites.

Fetherston, J.M., Stocklmayer, S.M., Stocklmayer, V.C. (2017) Gemstones of Western Australia, second edition. Geological Survey of Western Australia, Mineral Resources Bulletin 25, 356 pages, it is reported that:

"At the Yinnetharra North deposit, 1.5 km to the north of the Yinnetharra dravite openpit, schorl or black tourmaline was originally reported. In more recent years, it has been established that all tourmaline in this area is black dravite, with an MgO content of 9.85%. The Yinnetharra North deposit, on former mineral claim MC09/215, is in a black phlogopite schist containing large, euhedral black dravite rhombohedra, many with double terminations and internal zoning visible in thin section. Maximum crystal size is recorded as 60 mm in diameter and 23 cm in length".

Other Regions, Features and Areas containing this locality

References