North of 60 Mining News - The mining newspaper for Alaska and Canada's North

White Rock Minerals Ltd. May 20 announced the completion and preliminary results from a 311-mile (500 kilometers) airborne electromagnetic survey flown over its zinc-rich Red Mountain volcanogenic massive sulfide project in Alaska's Bonnifield Mining District.

The Australia-based exploration company said the geophysical survey, which also included the collection of magnetics data, used a state-of-the-art data collection and processing system to identify potential VMS conductors across its 183-square-mile (475 square kilometers) Red Mountain property.

When integrated with the surface geochemistry and geological information gathered by White Rock, these new data sets are expected to generate a list of high priority VMS targets for drilling that is getting underway this week.

White Rock says preliminary data from the electromagnetic survey highlights numerous conductivity features related to the geology, structure and associated known VMS mineralization on the Red Mountain property.

"We are very pleased with the preliminary results from using this modern, high-powered AEM (airborne electromagnetic) technique over our 475-square-kilometer strategic belt-scale regional tenement package," said White Rock Minerals Managing Director Matthew Gill. "This is the first step in our comprehensive exploration program for 2019."

While waiting for the final processing and interpretation of the results, White Rock and geophysicist are working with the preliminary data to identify conductivity features for immediate field exploration.

"Other activities this season will involve using satellite spectral analysis, on-ground geological reconnaissance and soil sampling. These activities will compliment planned electrical ground geophysics (CSAMT and MT) and a diamond drill program," said Gill.

CSAMT (controlled-source audio-frequency magnetotellurics) is a geophysical survey that proved to be successful in identifying zinc-rich VMS occurrences, such as the Hunter target discovered at Red Mountain last year.

The Red Mountain property already hosts two zinc-lead-copper-silver-gold deposits – Dry Creek and West Tundra Flats (WTF) – with resources that meet the standards of the Australian Joint Ore Reserves Committee. Combined, these deposits host 16.7 million metric tons of JORC-compliant inferred resources averaging 4.1 percent (1.49 billion pounds) zinc; 1.7 percent (630 million lb) lead; 0.2 percent (57.3 million lb) copper; 99 grams per metric ton (53.5 million ounces) silver; and 0.7 g/t (352,000 oz) gold.

Orientation work over these known deposits is what identified CSAMT as a good geophysical tool for reconnaissance work across the property.

While carrying out this reconnaissance program last year, crews identified a two-foot massive sulfide outcrop rich in sphalerite (zinc mineralization) and galena (lead mineralization) at Hunter, which is about 5,200 meters southeast of Dry Creek.

HR18-01, the Hunter discovery hole, cut 1.4 meters of massive sulfide averaging 17.4 percent zinc, 3.9 percent lead, 90 g/t silver and 1.6 percent copper. This equates to 25.8 percent zinc-equivalent when you consider the value of all the metals encountered.

Gill said this year's program is a follow-up to the successful discovery at Hunter.

"We will be testing the best of the regional targets defined by this multidisciplinary use of airborne EM, stream geochemical anomalies, new satellite defined alteration, whole rock lithogeochemical alteration, on-ground soil and rock geochemistry and on-ground electrical geophysics techniques," he said.

This exploration will be funded by Sandfire Resources NL, a mid-tier Australian mining company that can earn up to a 70 percent joint venture interest in Red Mountain by investing US$21.6 million into and completing a pre-feasibility study for developing a mine at the volcanogenic massive sulfide project over the next six years.

A US$4.3 million budget has been allotted for the 2019 program at Red Mountain.

–SHANE LASLEY