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Message: Importance of High Antimony associated with high gold - Australia

Importance of High Antimony associated with high gold - Australia

posted on Nov 20, 2007 01:00PM
World Mining News - Item [72003]: News Release
Northwest confirms high grade gold-antimony mineralisation at Green Stripe prospect in Western Australia
A limited near-surface follow-up drilling programme by Northwest has confirmed the discovery of high grade gold-antimony mineralisation at the company's Green Stripe prospect. This prospect is located within the Blue Spec Shear Project area, part of Northwest's Nullagine Gold Project.

Green Stripe
- 8m grading 10.23 g/t gold and 6m grading +2.5% antimony (from 34m down-hole)

The current results follow intersections announced in October including 7m grading 17.01 g/t gold and 3m grading 1.52% antimony (Sb) from 23m down hole and confirm the depth continuation of high-grade gold-antimony mineralisation ("Blue Spec style" mineralisation) at Green Stripe.

Green Stripe displays several similarities to the historic Blue Spec and Golden Spec high grade gold-antimony mines less than 4kms to the west along strike of the Blue Spec Shear, based on the high gold grade, presence of antimony, together with its structural style and architectural position.

Mining at Blue Spec averaged 25-30 g/t gold and +1.5% antimony and proceeded from surface to a depth of 320m. At Golden Spec mining averaged 15-22 g/t gold with significant amounts of antimony and proceeded from surface to a depth of only 120m. At each mine, drilling below the lowest workings has confirmed the strong continuation of high grade gold-antimony mineralisation.

Antimony has the potential to be a very valuable credit in connection with gold production from "Blue Spec style" mineralisation. At current prices, 1% antimony per tonne is the equivalent of approximately 2.5 g/t gold.

A significant new discovery

The discovery of Green Stripe is very significant as it demonstrates the potential of the Blue Spec Shear to host additional high grade gold-antimony deposits along its 18km extent, of which Northwest controls 16kms.

At Green Stripe the high grade mineralisation commences from 20m below the surface unlike Blue Spec and Golden Spec which had outcropping mineralisation. The near-surface expression of the high grade mineralisation at Green Stripe comprises low grade gold with the presence of antimony and low levels of arsenic. This forms a part of a larger "mineralisation halo" that surrounds the high grade mineralisation.

This halo feature goes some way to explaining why additional high grade gold-antimony deposits have not been discovered in the past along the Blue Spec Shear as the low grade gold/antimony/arsenic may have hidden the high grade gold-antimony mineralisation below surface.

It is significant to note that Green Stripe is immediately adjacent to a defined 800m soil geochemical anomaly. Reconnaissance RC drilling across this geochemical anomaly returned several wide low grade gold results which may represent a similar halo to that encountered above Green Stripe. The Golden Spec mine, which consists of three shoots, has a strike length of 350m.

Further drilling will be prioritised over Green Stripe in Northwest's first drilling campaign early next year to determine the extent of high-grade gold-antimony mineralisation at depth as the current programme only effectively tested within the first 40m from surface.

Advanced alteration and fluid-chemical techniques along with structural analysis of oriented diamond core will be utilised to refine depth targeting at Green Stripe and improve ore control understanding for targeting other identified high-priority targets within the Blue Spec Shear Project.

Antimony

High grade gold mineralisation on the Blue Spec Shear is associated with antimony (Sb). Antimony has a variety of industrial uses including flame retardants, semi-conductors and electronic components, batteries, anti-friction alloys, paints and tracer bullets.

The price of antimony (sold on the LME) has increased over 150% since 2001 to a 2005 price of around US$3,750 per tonne. At current prices, 1% antimony per tonne is the equivalent of approximately 2.5 g/t gold.

Metallurgy issues with antimony have been misconceived and overstated in the past. The separation of gold and antimony from "Blue Spec style" ore does not present any significant metallurgical issues, as demonstrated by the gold recovery rates from the most recent processing of "Blue Spec style" ore which ranged between 89-91% for gold.

The price outlook for antimony is very positive. World demand continues to be strong, underpinned by substantial growth in demand for flame retardants (a major consumer of antimony concentrate) and the growing demand for digital household appliances. Antimony trioxide sales are projected to increase 6.8% annually over the next three years.

In addition, China, the world's largest supplier of antimony, has suffered falling production as a result of depleted resources for some years. Chinese producers continue to suffer from on-going power shortages which restrict production. In August 2005, the Chinese State Council announced it will impose quotas on the exploitation and export of antimony at the end of 2005 as a result of general concerns over energy availability.

As a by-product of gold production, Northwest can produce antimony at a minimal cost. Northwest's CIP treatment plant, located within the Blue Spec Shear Project, was specifically designed to separate and capture antimony from the production process by employing pressure oxidation of the sulphide concentrate during cyanidization.

For more information, please contact:

John Merity
Managing Director
Tel: +61 2 9327 2990
Email: jmerity@nw-resources.com.au

Christian Easterday
Exploration Manager
Tel: +61 8 9322 8344
Email: ceasterday@nw-resources.com.au

or visit Northwest's website at www.nw-resources.com.au
Topics: Project Countries: Australia
Industries: Antimony Mining; Gold Mining
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