DeGrussa - DeGrussa/Conductor 1

In mid-2009, Sandfire discovered high-grade VMS copper-gold mineralisation at DeGrussa, located in the north-eastern portion of its Doolgunna Project tenements, which comprises the DeGrussa and underlying Conductor 1 lenses. A third lens was subsequently discovered at Conductor 4.

Initial drilling returned some of the best intersections seen in the Western Australian mining industry in recent times. For example, the discovery hole, DGDD-001, intersected a total of 78.3 metres of high-grade copper-gold mineralisation including:

  • 53.2m @ 17.3% Cu and 2.5g/t Au in DeGrussa; and 
  • 25.1m @ 3.4% Cu, 3.4g/t Au and 1.6% Zn in Conductor 1.

Hole DGDD-0014, which was located up-plunge of DGDD-001, intersected a total of 104.1 metres of copper-gold mineralisation with intersections including:

  • 9.1m @ 34.1% Cu, 3.3g/t Au and 29.9g/t Ag in DeGrussa;
  • 38.9m @ 4.7% Cu, 2.2g/t Au, 24.9g/t Ag and 2.9% Zn in DeGrussa;
  • 30m @ 8.6% Cu, 2.8g/t Au, 20.5g/t Ag and 0.7% Zn in DeGrussa; and 
  • 26.1m @ 7.3% Cu, 3.1g/t Au, 27.7g/t Ag and 1.9% Zn in Conductor 1.

Other notable intersections have included:

  • 50.1m @ 8.4% Cu, 2.9g/t Au, 1.6% Zn and 30.8g/t Ag from 242.5m in DGDD-007 (DeGrussa);
  • 42.0m @ 6.6% Cu, 2.4g/t Au, 1.4% Zn and 20.5g/t Ag from 245.0m in DGDD-008 (DeGrussa);
  • 8.9m @ 5.0% Cu, 1.5g/t Au, 1.4% Zn and 26.8g/t Ag from 378.1m in DGDD-007 (Conductor 1); and
  • 21.9m @ 5.0% Cu, 2.0g/t Au, 1.8% Zn and 14.9g/t Ag from 322.2m in DGDD-003 (Conductor 1).

Sandfire commenced a major program of diamond core drilling at the Doolgunna Project on 4 July 2009 designed to test the overall scale and dimensions of the mineralization at Conductor 1 and DeGrussa and in February 2010 announced a Phase I Indicated and Inferred resource estimate of of 7.13Mt at 5.2% copper, 1.9g/t gold and 15g/t silver for 372,000 tonnes of copper, 439,000 ounces of gold and 3.4Moz of silver.

View the full Phase I JORC resource estimate.

In-fill drilling was largely completed on a 40m by 40m surface drill-hole pattern during the second half of 2009 with a total of 88 diamond drill-holes completed by year-end, as shown in the diagram below:

Drilling continued to generate outstanding results, reinforcing the high grade, thick and consistent nature of the mineralisation in the DeGrussa and Conductor 1 lenses. Some of the more significant recent assay results include:

Doolgunna Drilling Sidebar

  • 40.8m @ 13.7% Cu, 2.4g/t Au in DGDD-015 (DeGrussa)
  • 39.5m @ 7.8% Cu, 3.0g/t Au in DGDD-064 (Conductor 1)
  • 37.6m @ 3.0% Cu, 1.8g/t Au in DGDD-041 (Conductor 1)
  • 37.1m @ 9.4% Cu, 3.7g/t Au in DGDD-021 (Conductor 1)
  • 36.9m @ 4.0% Cu, 1.7g/t Au in DGDD-017 (Conductor 1)
  • 33.7m @ 7.0% Cu, 1.3g/t Au in DGDD-049 (Conductor 1)
  • 31.4m @ 4.6% Cu, 2.1g/t Au in DGDD-076 (Conductor 1)
  • 28.2m @ 2.8% Cu, 3.8g/t Au in DGDD-012 (DeGrussa Oxide)
  • 26.0m @ 3.8% Cu, 1.4g/t Au in DGDD-079 (Conductor 1)
  • 25.9m @ 4.7% Cu, 2.2g/t Au in DGDD-075 (Conductor 1)
  • 24.6m @ 9.4% Cu, 1.8g/t Au in DGDD-012 (Conductor 1)
  • 23.7m @ 5.4% Cu, 1.9g/t Au in DGDD-073 (Conductor 1)
  • 21.9m @ 6.3% Cu, 0.9g/t Au in DGDD-077 (Conductor 1)
  • 20.0m @ 4.8% Cu, 0.8g/t Au and 14.9m @ 4.7% Cu, 1.9g/t Au in DGDD-081A (Conductor 1)
  • 13.6m @ 10.2% Cu, 2.8g/t Au in DGDD-024 (Conductor 1)
  • 8.9m @ 10.6% Cu, 3.0g/t Au in DGDD-080 (Conductor 1)
  • 6.8m @ 14.8% Cu, 1.7/t Au in DGDD-0085 (Conductor 1)
  • 2.1m @ 17.8% Cu, 7.5g/t Au in DGDD-069 (DeGrussa)

The dotted line in the figure to the right (click for a larger version) shows the outline of the drill hole pattern which has successfully intersected high-grade copper-gold mineralisation within Conductor 1. 

The results are consistent with Sandfire’s geological model for the Conductor 1 and DeGrussa deposits.

The DeGrussa deposit comprises a steeply dipping to near-vertical zone of high-grade copper-gold mineralization (+zinc and silver).

The underlying Conductor 1 deposit has been outlined over a lateral strike extent of 320-350 metres, dipping steeply to the south to a vertical depth of over 400 metres.