THE BULGERA GOLD
On 9 July 2019 Norwest Minerals announced the 100% acquisition of the Bulgera Gold Project (“Bulgera”) located 200 kilometres north of Meekatharra with an existing haul road to the Plutonic Gold operation. Bulgera’s historic exploration, development and mining database shows multiple gold lodes extending below the shallow open cut pits and along the 5-kilometre strike of the sheared greenstone package.
Historical mining at Bulgera totals 441,000 tonnes grading 1.65g/t Au producing 23,400 ounces of gold. Extraction, haulage and processing occurred when gold was selling at or below A$570 per ounce. With the gold price now exceeding A$2,500 per ounce, Norwest believes further resource definition and exploration work at Bulgera will add significant value to this asset.
The Bulgera Gold Project comprises two granted exploration licences, E52/3316 and E52/3276, covering 36.8km² over the northeast end of the Plutonic Well Greenstone Belt, 200km northeast of Meekatharra. The project is located 20km northeast of the Marymia mining centre and 48km via existing haul road from the operating Plutonic gold mine which has produced over 5.5 million ounces of gold since 1990. The Plutonic mine is owned by Toronto listed Superior Gold Inc. (TSX-V:SGI).
The project contains four shallow open pits that have undergone two phases of mining between 1996 and 1998 and again between 2003 and 2004. Mining of the four pits being Bulgera, Mercuri, Venus and Price produced a reported 440,799 tonnes of ore @ 1.65 g/t Au for 23,398 ounces. The ore was treated at the Marymia mining centre during the first phase and the Plutonic processing facility during the second phase.
The Bulgera greenstone package has been interpreted as a faulted extension of the Marymia mine sequence across a system of curved thrusts where Marymia and Bulgera are offset. This is supported by the similarity in lithologies between the deposits and the magnetics which show the drag of the Bulgera trends into the interpreted fault structures1.
Vango Mining Ltd (ASX: VAN) is aggressively exploring the Marymia tenements along the mafic-ultramafic mine sequence where they have made a number of high-grade gold discoveries including the Trident deposit being 1.59Mt @ 8g/t gold for 410,000 ounces.
The Bulgera Gold Project location is endowed with infrastructure including the large Plutonic Gold Mine operating nearby, 2 x gas-fired power stations, overhead transmission power lines, bore fields, airstrip and camp facilities.
Norwest acquired the Bulgera Gold Project for $220,000 in July 2019 and in September 2019 reported a JORC resource totaling 2Mt @1.03g/t gold for 65,500 ounces.
The resource was upgraded in April 2020 to 2.92Mt grading 1.0 g/t for 93,880 ounces of gold following Norwest’s maiden 46-hole, 5,840 metre RC resource drilling programme completed 17 December 2019.
Resource Drilling and Gold Resource Estimation
The gold resources at Bulgera were increased in April 2020 following reverse circulation (RC) drilling completed in December 2019. The maiden RC drilling programme targeted mineralisation below and adjacent to the historic Mercuri and Bulgera open cut pits. The 46-hole, 5,860 metre programme was designed to: 1) confirm pre-2004 drilling results, 2) convert low-confidence Inferred Resources to higher-confidence Indicated resources and 3) test the down dip continuity of gold mineralisation beyond existing model limits.
Norwest twinned 10 historic (pre-2004) RC drill holes with results confirming geological features, gold tenor and intercept widths of the majority of holes duplicated. Infill drilling targeted zones containing low confidence Inferred resources, with the greater drill hole density resulting in a 61% increase to the higher confidence Indicated resource category.
The deeper RC step-out drilling produced a number of exciting gold intercepts including:
- 3m @ 10.5 g/t Au from 84m in BRC19041
- 4m @ 8 g/t Au from 71m in BRC19043
- 3m @ 3 g/t Au from 67m in BRC19014
- 2m @ 2 g/t Au from 96m in BRC19026
This latest RC drilling data was combined with Bulgera’s extensive historical exploration, development and mining database. Modelling of the new drilling data was undertaken by independent resource experts Hyland Geological and Mining Consultants (“HGMC”) using MineSight software which was utilised to construct the block models and run geostatistical and variography calculations. Kriging algorithms were applied to determine block gold grades and resource confidence levels.
The JORC 2012 compliant Mineral Resource for the Bulgera Gold project applying a 0.6g/t lower Au cut-off stands at:
|Indicated Resources||Inferred Resources||Total Resources|
|Mt||Au (g/t)||Au Ozs||Mt||Au (g/t)||Au Ozs||Mt||Au (g/t)||Au Ozs|
The Bulgera acquisition cost of $220,000 combined with the cost of the maiden RC drilling programme brings the average cost per JORC resource ounce to A$11.
Norwest is using aircore drilling to test a number of gold targets identified immediately along strike of the historic Bulgera Mining Centre.
The gold targets include geophysical features, anomalous gold-in-soil zones and areas where thick transport cover has likely masked anomalous gold in historical surface samples.
Of particular interest is a geophysical feature located southwest of the Bulgera Mining Centre showing a disruption of the greenstone mine sequence and coinciding with several high-grade gold surface samples collected last month by Norwest. Of the seven samples collected, one returned a gold assay of 86 g/t and another assayed 4 g/t gold.
1. Richards, R., May 2016. Information Memorandum, Bulgera Gold Project, Plutonic Well Greenstone Belt, WA