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

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

Well-known locality for very large and well-formed dark brown dravite crystals. (Reports of "povondraite" from here are dubious). The deposit was discovered in 1918. In 1968 A. Soklich claimed the area and started mining. During the 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, and provided the following information.

It consists on two pits 1km apart roughly parallel on strike nth nth west. Brown dravite occurs at the Sth. pit, and black dravite "Povondraite" in the Nth 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 exist cutting across strike of the tourmaline-bearing schists. Regional metamorphosis and deformation of metasediments with highly hydrothermally altered zones allowed tourmaline crystals to form in the mica schists. Dravite has associated apatite crystals up to 125mm but these are very rare Dravite crystals up to 7kg have been found. There are different zones existing in 2 contact zones producing smaller crystals and central zone producing giant dravites.

The main south deposit is about 5 meters wide and runs for a few hundred meters. The existing pit is about 30 meters long and has a very curious friendly goanna living in there. The pit contains highly fluorescent chalcedony under both UV and short wavelengths, and exists in fracture lines to the surface.

Most of the brown dravite specimens on the market come from the Soklich mining period (1968-1971), with crystals found sporadically within pockets. Near surface crystals were of poor quality due to fracturing, commonly encrusted by secondary opal and carbonates from weathering.

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".

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