Ferndale pegmatite, Balingup, Donnybrook-Balingup Shire, Western Australia, Australiai

Regional Level Types
Ferndale pegmatite	Pegmatite
Balingup	- not defined -
Donnybrook-Balingup Shire	Shire
Western Australia	State
Australia	Country

This simple pegmatite is found 9 kilometres south west of Balingup. It is on private property, but the owners rent a cottage to holiday makers (called Stoneridge Cottage), which is sited next to the old quarry, and provides an easy way to access the deposit.

The pegmatite was probably discovered around 1900 during the tin mining boom in the Greenbushes area, but the lack of cassiterite at the pegmatite meant it was ignored for many years. Mining started in 1930 for potassium feldspar, used in ceramics, and continued on an irregular basis until 1959. Ten tonnes of beryl was also mined here between 1939 to 1944. The quarry is 20 metres in diameter and 10 metres deep. When the writer visited it was badly overgrown.

The pegmatite was mapped in 1956, as an University of Western Australia honours project, by J.H. Leow and S.K. Chung. For many years after students from the university travelled to the location to study pegmatite geology.

The pegmatite has intruded into the Ballingup Metamorphic Belt. It is a simple beryl-feldspar pegmatite. It is 640 metres long by 10 to 34 metres wide, and trends northwest west. It shows a fine grained quartz-microcline-plagioclase-muscovite contact zone, a medium grained quartz-microcline-muscovite wall zone, an incomplete microcline intermediate zone, and a quartz core.

The main interest at the quarry is beryl. These are typically large 30 cm long by 20 cm wide, bluish-grey, opaque, with only one clean face. Other species can find themselves attached to the beryl, including tiny 1cm ferrocolumbite and ilmenite crystals. Schorl is rare, but the writer has a specimen, showing massive schorl with 1-2cm dodecahedron spessartine-almandine garnet crystals. Spinel is also said to be found rarely, as brownish octahedrons less than 2 cm in length.

Other Regions, Features and Areas containing this locality

References