Pend Oreille, located in the northern part of Idaho, USA, is known for its rich mineral deposits, particularly silver, lead, zinc, and copper. Historically, mining has played a significant role in the region’s economy and development. The Coeur d’Alene mining district, which includes Pend Oreille County, has been a major producer of these metals since the late 19th century.
Exploration activities in Pend Oreille County have focused on identifying and developing new mineral deposits, primarily targeting base metals like lead, zinc, and copper, as well as precious metals such as silver. The region’s geology is favorable for these deposits, with a mix of volcanic and sedimentary rocks providing diverse mineralization opportunities.
There is ongoing exploration interest in Pend Oreille, USA, for other minerals as well, including copper, gold, and potentially critical minerals like cobalt and lithium, given the increasing demand for these resources.
Finding lead–zinc sulphides from surface
A self-funded blind test of Atomic Dielectric Resonance (ADR) over a carbonate-hosted Zn–Pb sulphide system — with a true positive and a true negative.
See before you drill.
VEXRAD ran a self-funded proof of concept to test whether ADR could identify lead–zinc massive sulphide directly from surface, over a carbonate-hosted Zn–Pb system worked by a major base-metals producer in the northwestern United States. Six virtual boreholes — five from surface and one underground — were interpreted using a Weighted Sulphide Correlation Criterion (WSCC) and then checked against the operator’s drill logs. The result did the two things a sceptical geologist most wants to see: where the drill hit massive sulphide, WSCC flagged it (a true positive); where the drill found none, WSCC stayed low (a true negative). An independent underground scan then corroborated the surface highs.
Detect sulphide from ground level, blind
The aim was deliberately hard: identify subsurface sulphide zones from ground level, with no reliance on drilling to guide the interpretation. ADR returns a depth profile — a “virtual borehole” — of the subsurface’s material-property response. The WSCC method weights several ADR parameters into a single index tuned to the signature of massive sulphide, so a high WSCC reading is a candidate sulphide zone. Five surface virtual boreholes and one underground virtual borehole were acquired and interpreted, then compared with the operator’s logged holes.
Assessed against the drill logs
Each finding is reported under VEXRAD’s four-tier evidence standard — nothing is claimed beyond what the drilling supports.
| Hole / feature | ADR (WSCC) result | Drill-log ground truth | Read |
|---|---|---|---|
| MX03, ~500–550 m | Highest WSCC in the survey | Massive sulphide | Validated — true positive |
| MX03 & MX19, ~400 m | WSCC peak in both boreholes | Massive sulphide | Validated |
| MXP1 (blind V-bore) | Same WSCC trend, interpreted blind | Consistent with adjacent holes | Candidate |
| MX73 | Low WSCC (minor peak ties to a ~200 m dike) | No sulphide logged | Validated — true negative |
| Underground V-bore | Highest WSCC values | Coincide with the surface-validated highs | Validated — cross-check |
ADR flagged sulphide where it was present and stayed quiet where it was absent. A true positive proves detection; a true negative proves discrimination — the harder, more valuable half of the test.
What this doesn’t claim
- This was a proof of concept, not a resource study; WSCC flags the presence of sulphide, not its grade or tonnage.
- Validation is against the operator’s drill logs; the correlations are strong but interpretive.
- The underground virtual borehole’s exact scan location was not recorded and had to be approximated, so its cross-check is indicative rather than precise.
We report these plainly. A result is only worth as much as the honesty around it.
What it means for explorers
For a massive-sulphide explorer, the expensive risk is drilling barren ground. This test shows ADR reading sulphide presence from surface, blind — hitting where the drill hit and, just as importantly, staying low where it didn’t. On a live project the method is sharper still: calibrated against one or two of your logged holes first, then used to rank targets before you commit to diamond drilling.
Talk to us about your project