SCOTTSDALE, Ariz., Dec. 04, 2017 (GLOBE NEWSWIRE) -- TriStar Gold Inc. (TSXV:TSG) (the “Company” or “TriStar”) has completed an updated mineral resource estimate for the Castelo de Sonhos gold project using all available data, including assays from the 37 drill holes that were not available for the September 18, 2017 resource estimation. Key highlights are:
- Mineral resource (0.4 g/t cut-off) of
• Indicated
• 8.9 million tonnes,
• at 1.8 g/t,
• containing 0.5 million ounces of gold
• Inferred
• 26.3 million tonnes,
• at 1.2 g/t,
• containing 1.0 million ounces of gold - Substantial amounts of Esperança Central and South still untested
- Esperança East and West will be drill tested in 2018
“The resource is growing as anticipated and continues to validate the predictions of the exploration target range. We look forward to drilling in 2018 aimed at further expanding the resource and supplying all the data necessary for the scoping study,” says Nick Appleyard, TriStar’s President and CEO, “CDS continues to deliver and the resource has grown by over 400% in the last 18 months, and now our confidence levels are growing as well. We are particularly pleased with the strong grade of the Indicated resources, at 1.8 g/t, which is due to our ability to use petrophysics and televiewer to identify marker horizons that establish continuity between our 50m drill holes.”
Table 1. Mineral resource estimate1 for the Castelo de Sonhos gold project (with an effective date of December 4, 2017) above a reporting cutoff 2 of 0.4 g/t Au.
| Region | Resource Category | Tonnage (Mt) |
Grade (g/t Au) |
Metal Content3 (Moz Au) |
| Esperança South | Indicated | 8.9 | 1.8 | 0.5 |
| Inferred | 14.9 | 1.2 | 0.6 | |
| Esperança Center | Indicated | 0 | 0 | 0 |
| Inferred | 11.3 | 1.0 | 0.4 | |
| Project Total | Indicated | 8.9 | 1.8 | 0.5 |
| Inferred | 26.2 | 1.2 | 1.0 |
1Numbers have been rounded to reflect the precision of Inferred and Indicated mineral resource estimates.
2The reporting cutoff corresponds to the approximate marginal cutoff for an open pit with total operating cost (non-waste mining + processing + G&A) of $US 15.00/t, metallurgical recovery of 98% and a gold price of $US 1,200/oz. These are mineral resources and not reserves and as such do not have demonstrated economic viability.
3The metal content estimates reflect gold in situ, and do not include factors such as external dilution, mining losses and process recovery losses.
4TriStar is not aware of any environmental, permitting, legal, title, taxation, socio-economic, marketing or political factors that might materially affect these mineral resource estimates.
5TriStar intends to file a new NI 43-101 technical report within 45 days in support of this new mineral resource estimate.
Resource estimation method
The resource is constrained by a mineralized envelope that corresponds to the conglomeratic band of the paleo-placer, honouring its outcrop location and surface measurements of its bedding orientations, and extending into the upper arenite where drilling has confirmed that the base of the upper arenite contains remobilized gold. All drill hole assays were capped at 20 g/t.
This resource update was done using inverse-distance-cubed (ID3) interpolation of grades from drill holes into 5x5x2m blocks. The search strategy, guided by variogram analysis, uses a flattened ellipse, with ranges of 100m in the bedding direction and 10m perpendicular to bedding. Heavy mineral bands in optical televiewer (OTV) images were used to establish local bedding orientations. Grade estimation was performed separately within each of three major stratigraphic units that comprise the conglomerate band, and within two more strongly mineralized reefs that occur at the boundaries between these units. Assay data, lithology logs and petrophysical signatures were used to identify marker horizons at the boundaries of these units. The reefs that occur at the boundaries between the three major units are 10-20m thick and appear to be very continuous.
As with the previous resource model, this new resource estimate was checked against the grade-tonnage distribution predicted by a global change of support procedure, assuming 5x5x2m selective mining units. The grade, tonnage and metal content predicted by this global procedure are all within 10% of the values reported from the ID3 block model, which has the advantage of providing local detail that enables checking of the modeling of marker horizons and continuity directions.
Resource classification
The mineral resources have been reported from inside a pit shell using parameters of $1,500 gold, 98% metallurgical recovery, 55-degree pit slopes and operating costs of process $10/t, G&A $1.50/t and contract mining at $3/t. Within the pit shell material above a cut-off grade of 0.4 g/t was classified as Indicated resources in areas with 50m drilling, where at least three separate drill holes are available for grade estimation, the closest of which is within half the range of the variogram. Areas with 100m drilling support Inferred resources, with samples within the range of the variogram and usually from more than one drill hole. Where hole spacing is wider than 100m, as on the west side of Esperança South (see Figure 1), no resources were estimated, even where the drilling contains significant intervals above the reporting cutoff; these require further drilling before they can be incorporated into a future expanded areal footprint of the resource.
Qualified Person
Mo Srivastava (P.Geo.) VP of TriStar the Qualified Person for the mineral resource estimates presented in this press release, has approved its publication.
About TriStar:
TriStar Gold is an exploration and development company focused on precious metals properties in the Americas that have potential to become significant producing mines. The Company’s current flagship property is Castelo de Sonhos in Pará State, Brazil. The Company’s shares are listed on the TSX Venture Exchange under the symbol TSG. Further information is available at www.tristargold.com.
