Moolyella pegmatite field, Marble Bar, East Pilbara Shire, Western Australia, Australiai

Regional Level Types
Moolyella pegmatite field	Pegmatite Field
Marble Bar	- not defined -
East Pilbara Shire	Shire
Western Australia	State
Australia	Country

Four to eight kilometres after the Marble Bar turnoff, take the dirt road north-east to the former Pilbara Tin office and plant, and the pegmatites are in this general area. Located east of the Marble Bar townsite.

The pegmatites were discovered in 1898 with 76.5 tonnes of cassiterite concentrate mined from alluvium. Peak production was in 1907, but gradually declined and ceased by 1921. From 1927 to 1934 the field was mined by eighty to ninety local aboriginals. In 1958, local individual tin miners formed a co-operative called Mineral Concentrates Limited and mining resumed. This organisation was purchased by Kathleen Investments Pty Ltd in 1964, and its name changed to Pilbara Tin Pty Ltd. In 1975 this was sold again and the name changed to Pilbara Concentrates Pty Ltd.

There are a number of pegmatites on the field. The reference describes the six largest or most important.
1. Two north trending pegmatites are just west of Swan Gully. GPS co-ordinates suggested are 800,555E 7,658,853N UTM50 AGD84, and 800,784E 7,659,545N UTM50 GDA94. The western vein is one metre thick and dips 20 degrees to the east, with cassiterite crystals up to 2.5cm in diameter. The eastern pegmatite is similar with two pits on it. The pegmatites are believed to be 300 metres long and up to three metres wide , quartz-albite-microcline, with cassiterite, columbite-tantalite and magnetite mined from them.
2. A large north trending pegmatite on the east side of Universal Gully. GPS co-ordinates suggested are 801,830E 7,659,218N UTM50 AGD84 or 801,734E 7,659,928N UTM50 GDA94. A forty metre bulldozer cut has gone through the pegmatite containing cassiterite.
3. Eley's Lode being two pegmatite veins fifteen metres apart, dipping to the south-east. GPS co-ordinates suggested are 799,720E 7,658,672N UTM50 AGD84 or 799,719E 7,659,299N UTM50 GDA94. The south-eastern vein was mined along its 20 metre strike to 2 metres, and the western vein was mined from a 10 metre long cut.
4. Pegmatite on former MC901 with a few shallow pits along its 25 metre strike.
5. Atkin's Lode, 3.2 kilometres south of Mud Springs Well, but could now be buried under mullock.
6. A small pocket of manganotantalite discovered by J.A. Cotton in 1938, from a microcline-albite pegmatite, eight kilometres north of Moolyella.

The pegmatites are found along the edge of the Moolyella Adamellite. These cassiterite bearing pegmatites have intruded into tension fractures within the gneiss granite of the Mount Edgar Batholith.

The Simpson Mineral Collection of the Western Australian Museum holds a number of specimens from various locations within the Moolyella pegmatite field.

Geochronology

Mineralization age: Mesoarchean : 2868 ± 53 Ma to 2830 ± 30 Ma

Important note: This table is based only on rock and mineral ages recorded on mindat.org for this locality and is not necessarily a complete representation of the geochronology, but does give an indication of possible mineralization events relevant to this locality. As more age information is added this table may expand in the future. A break in the table simply indicates a lack of data entered here, not necessarily a break in the geologic sequence. Grey background entries are from different, related, localities.

Geologic Time				Rocks, Minerals and Events
Precambrian
	Archean
		Mesoarchean		ⓘ Muscovite 2830 ± 30 Ma ⓘ Cassiterite (youngest age) 2839 ± 16 Ma ⓘ Cassiterite (oldest age) 2868 ± 53 Ma

Other Regions, Features and Areas containing this locality

References