Mount Deans pegmatite field, Norseman, Dundas Shire, Western Australia, Australiai

Regional Level Types
Mount Deans pegmatite field	Pegmatite Field
Norseman	Town
Dundas Shire	Shire
Western Australia	State
Australia	Country

Located nine kilometres south of Norseman, and a couple of kilometres east of the highway. The field was mined for cassiterite between 1965-1967, producing 7.18 tonnes of concentrate. Between 1966 -1985 Norseman Gold Mines NL, and CRA Exploration Pty Ltd, explored the area but did not find cassiterite or tantalum in economic amounts. In 2001 Tantalum Australia Pty Ltd extensively drilled the pegmatite and stated the deposit contained 9.1 million tonnes of ore. They were investigating mining the deposit, however when the writer visited in 2011, no mining had taken place. It is common for exploration companies here in Western Australia to produce positive reports on mineral finds, that never have any likelihood of mining taking place. In 2003, Amit Eliyahu, completed his University of Western Australia thesis on the pegmatite.

The area has a swarm of 71 recognised pegmatites covering 4.5 by 1.5 kilometres trending north north-west. Many of the pegmatites are 500-2000 metres in length and 0.3-7.5 metres thick, with a few 20 metres thick. The pegmatites have an upper portion quartz poor, cleavelandite rich marginal layer, which is where most of the cassiterite and tantalum is found.

There are a large number of trenches, diggings and small open cut pits along the southern side of the access track covering about two kilometres. Two of the larger pits are called Dave's Open Cut (at the far end if travelling from Norseman), and Poldark's Open Cut, about half way along the diggings. Cassiterite, lepidolite and petalite specimens are reasonably common to find, while blue elbaite and pink beryl is more difficult.

Geochronology

Mineralization age: Neoarchean : 2620 ± 36 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
		Neoarchean		ⓘ Albite 2620 ± 36 Ma ⓘ Garnet Group 2620 ± 36 Ma

Fossils

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References