FACTBOX-Combined metals assets of Xstrata and Anglo

June 22 (Reuters) - Swiss-based miner Xstrata Plc is seeking a merger of equals with rival Anglo American Plc, which would push the group to the top of the world's rankings in copper mining.

A merged company, worth about $68 billion, would also be the world's No.1 zinc miner and move one place up the ladder in nickel mining. COPPER

The proposed combination would create the world's number one copper mine producer, with output of 1.579 million tonnes on a 2008 basis, according to industry consultants CRU Group.

Chilean state-owned company Codelco is currently the world's largest copper miner.

The combined entity would also be the world's third biggest copper refiner, with 1.033 million tonnes on a 2008 basis.

Anglo's copper assets include the Los Bronces expansion in Chile, the Quellaveco project in Peru and Michiquillay.

The two companies also hold 44 percent stakes each in the large Collahusi mine in Chile.

Xstrata's other copper operations and projects include - Antamina and Las Bambas in Chile, El Pachon in Argentina and Ernest Henry.

ZINC

A merged company would be the world's largest zinc mine producer on a western world basis, CRU figures suggest.

They would have produced a combined 1.316 million tonnes, based on 2008 figures, ahead of Teck Cominco with 663,000 tonnes.

In refined production the combination would briefly move up to fifth place with around 650,000 tonnes of metal. But India's Hindustan Zinc continues to expand and would overtake Xstrata/Anglo within a matter of months.

The 150,000 tonnes per year (tpy) Skorpion operation in Namibia is Anglo's key zinc asset.

Anglo's lead mines are not particularly large and their addition to Xstrata's assets would not alter world rankings.

NICKEL

Last year Xstrata ranked fourth place in terms of 2008 global nickel mine output, with Anglo 11th.

Based on those figures, a combined entity would move up to third place with total output of 135,000 tonnes.

The world's top nickel producer, Russia's Norilsk Nickel recently said it aims to produce 285,000-300,000 tonnes of nickel this year.

PLATINUM

Anglo owns the world's largest platinum producer, South Africa's Anglo Platinum, which produced around 2.4 million oz of the precious metal last year.

Xstrata is building up its platinum business in South Africa.

OTHER ASSETS

Xstrata says it is the world's largest producer of ferro-chrome and a leading producer of primary vanadium.

It also says it is the world's largest exporter of thermal coal.

Anglo says it is a leading producer of iron ore, manganese and carbon steel.

It also produces coal, industrial minerals and owns 45 percent of the world's largest diamonds producer De Beers.

(Sources: CRU Group, company reports, Reuters)

(Compiled by Karen Norton; edited by William Hardy)