TORONTO, Jan. 03, 2018 (GLOBE NEWSWIRE) -- Inventus Mining Corp. (TSX VENTURE:IVS) (“Inventus” or the “Company”) is pleased to announce the results from a 1,000-tonne bulk sample from the Pardo Paleoplacer Gold Project (“Pardo”) near Sudbury, Ontario. The total gold content of the bulk sample was calculated to be 4.16 kg (133.8 Troy ounces) of gold, equivalent to 4.2 grams per tonne (gpt). A total of 3.72 kg (119.5 Troy ounces) of gold was recovered from 985 dry tonnes of mill feed. The tailings are estimated to contain an additional 0.44 kg (14.2 Troy ounces) of gold, indicating a recovery rate for gold of approximately 89%. Diamond drilling in the bulk sample area prior to extraction consisted of eleven holes that returned an average grade of 1.34 gpt gold. Processing of the bulk sample demonstrates a significant increase in the gold grade when compared to assays of diamond drill core.
“Paleoplacer gold deposits are enigmatic by nature and do not reveal their secrets easily. The results of this initial bulk sample are highly encouraging and highlight the critical importance of bulk sampling for grade estimation. Assaying of drill core alone is insufficient to determine the actual grade of the mineralized boulder conglomerate. The success of this bulk sample has increased our confidence about the overall grade of the boulder conglomerate, confirming our belief that continued investment in exploration and additional bulk sampling is warranted,” said Stefan Spears, Chairman and CEO.
Bulk Sample Procedure
The bulk sample was extracted from a pit with a surface area of 240 square metres. Approximately 1,000 wet tonnes was blasted and the run-of-mine material was transported by truck to McEwen Mining’s Black Fox Mill (the “BFM”) near Timmins, Ontario. The BFM is a conventional gold mill comprised of a three-stage comminution circuit, cyanide leach and carbon-in-leach (CIL) gold recovery. Prior to batch processing of the bulk sample the mill circuit was purged with 1,000 tonnes of barren sand. The processing of sand is designed to cleanse the milling equipment and displace the ore in the first 800-tonne capacity leach tank.
At the BFM the Pardo material was crushed and milled to approximately 75 microns and leached for a minimum of 30 hours. Grade and recovery calculations were made based on a total in-circuit inventory before and after the bulk sample was processed. Samples of the leach solution and leached solids were also taken after 30 hours and returned a combined assay of 4.1 gpt gold, which is consistent with the in-circuit inventory calculation.
Bulk Sample Drilling
Prior to the extraction of the bulk sample, a pattern of eleven diamond drill holes was completed on five-metre centers of the bulk sample area in order to compare drilled gold grades to bulk sample grade for the Mississagi Boulder Conglomerate (MiBC)(see Figure 1). The drill core was sampled and assayed using the same whole core methodology developed during the 2017 exploration program. The average assayed grade and thickness of the target MiBC was 1.34 gpt over 2.54 m. The grades of the MiBC was highly variable between holes, ranging from a low of 0.17 gpt over 2.44 m to a high of 4.07 gpt over 2.17 m. Visible gold was noted in 5 of the 11 holes (see Table 1).
Figure 1 – Trench 1 Bulk Sample Area (Pardo Project) - Jan 3, 2018
Systematic measurements of clast dimensions taken along the drill core intercept of MiBC indicate that the boulder conglomerate on average is composed of 26% matrix and 74% clasts. Gold is contained within the matrix and the clasts are barren of gold, therefore the bulk sample is composed of 26% gold bearing matrix and 74% un-mineralized waste rock. In a news release dated April 5, 2017 Inventus discussed the possible application of advanced ore sorting techniques, and demonstrated in a scoping level study, the encouraging potential to sort gold bearing matrix from the un-mineralized clasts. We plan to continue evaluating the use of ore sorting as a means of efficiently processing larger bulk samples.
Risk Factors
All of the bulk sample material was removed from a single location known as Trench 1 (see Figure 1). Trench 1 was selected because it was considered to have representative grade, and was ideally located for easy extraction. There is no assurance that mining or bulk sampling in another location at Pardo would result in similar gold content or recovery.
The BFM is a commercially operating gold processing facility that receives feed from the Back Fox Mine and from third party custom milling clients. To the best of our knowledge, the mill operates using industry standard practices for sampling and quality assurance, but is not intended for the analysis of small batch bulk samples. The minimum custom milling batch size normally required by the BFM is 5,000 tonnes. The mill operator’s standard procedure prior to processing custom feed is to purge the mill circuit by processing one thousand tonnes of barren sand. However, it is possible that preexisting gold contained in the circuit was flushed out while processing the bulk sample. Similarly, the bulk sample could have deposit gold residue in the circuit. It is unknown to what extent this may have contributed to inaccuracies in the results. There is no certification as to the precision of the results and readers should use caution in their use and interpretation.
There is currently no NI 43-101 mineral resource estimate established anywhere on the Pardo property.
Mining dilution for the bulk sample was estimated to be 7% based on geologists’ field observations, mostly as a result of over-blasting of the footwall in the pit. Ore loss was estimated at 0.5%, due to over-blasting of the hanging wall, and minor losses during transportation and handling.
Interests of Related Parties
Inventus and McEwen Mining are related parties, meaning that members of management have economic interests in both companies. Stefan Spears, Chairman and CEO of Inventus, currently provides consulting services to McEwen Mining in areas that are unrelated to Inventus. Rob McEwen, Chairman and Chief Owner of McEwen Mining, is a significant shareholder of both companies, owning approximately 20% and 24% of Inventus and McEwen Mining respectively.
The milling agreement between Inventus and McEwen Mining was on terms believed to be commercially reasonable. The milling agreement specified a base processing fee of $42.00 per tonne, and a provision for cost recovery of assaying and other miscellaneous expenses. It is expected that Inventus will pay McEwen Mining approximately $50,000 in connection with the services it provided processing the bulk sample. McEwen Mining will remit the net proceeds from the sale of the gold produced to Inventus. Inventus does not have an agreement with McEwen Mining, or any other service provider, for the processing of future bulk samples and as such there is no guarantee that the foregoing costs would be representative of future costs.
Table 1 – Trench 1 Drill Results
| Hole ID | From (m) | To (m) | Thickness (m) | Gold Fire Assay Grade (gpt) | Visible Gold (VG) Observations | % Matrix in Conglomerate | |
| TR1-17-01 | 3.14 | 5.62 | 2.48 | 0.30 | 31.1 | % | |
| TR1-17-02 | 2.98 | 5.50 | 2.52 | 0.71 | VG @ 3.32m & 3.65m | 26.0 | % |
| Including | 2.98 | 3.82 | 0.84 | 2.12 | |||
| TR1-17-03 | 2.00 | 4.85 | 2.85 | 1.06 | VG @ 2.75m | 26.6 | % |
| Including | 2.60 | 3.18 | 0.58 | 3.34 | |||
| TR1-17-04 | 1.88 | 4.77 | 2.89 | 1.39 | 19.3 | % | |
| Including | 3.30 | 4.00 | 0.70 | 4.88 | |||
| TR1-17-05 | 2.79 | 5.23 | 2.44 | 0.17 | 33.4 | % | |
| TR1-17-06 | 2.05 | 4.80 | 2.75 | 3.79 | VG @ 2.67m | 17.7 | % |
| Including | 2.05 | 2.70 | 0.65 | 14.20 | |||
| TR1-17-07 | 2.05 | 4.67 | 2.62 | 1.62 | 24.8 | % | |
| Including | 3.60 | 4.15 | 0.55 | 3.58 | |||
| TR1-17-08 | 1.64 | 3.52 | 1.88 | 0.93 | VG @ 1.96m | 29.4 | % |
| TR1-17-09 | 2.38 | 5.30 | 2.92 | 0.30 | 19.7 | % | |
| TR1-17-10 | 2.48 | 4.90 | 2.42 | 0.39 | 32.5 | % | |
| TR1-17-11 | 1.63 | 3.80 | 2.17 | 4.07 | VG @ 2.41m & 2.42m | 28.4 | % |
| Including | 2.20 | 2.75 | 0.55 | 15.01 | |||
| Thickness (m) | Grade (gpt) | % Matrix in Conglomerate | |||||
| Bulk Sample Diamond Drilling Average | 2.54 | 1.34 | 26.3 | % | |||
About Inventus Mining Corp.
Inventus is a mineral exploration and development company focused on the world-class mining district of Sudbury, Ontario. Our principal asset is a 100% interest in the advanced exploration stage Pardo Paleoplacer Gold Project located 65 km northeast of Sudbury. Pardo is the first important paleoplacer gold discovery found in North America. Inventus has 106,971,069 common shares outstanding (116,965,236 shares on a fully diluted basis).
