SCOTTSDALE, AZ--(Marketwired - September 18, 2017) - TriStar Gold Inc. (the "Company" or "TriStar") (TSX VENTURE: TSG) has received from CSA Global ("CSA") an independent mineral resource estimate for the Castelo de Sonhos gold project. Key highlights are:
- Inferred mineral resource (0.4 g/t cut-off) of
- 31 million tonnes,
- at 1.3 g/t,
- containing 1.3 million ounces of gold
- Results validate the exploration target range projections that have been utilized to guide drill targets
- Approximately 30% of the assays from the current RC program are still pending for inclusion in an updated resource estimate
- Substantial amounts of Esperança Central and South still untested
- Esperança East and West will be drill tested in 2018
- Preliminary economic assessment to be based on updated resource
"We are very pleased to see the predictions of the exploration target range now being validated by hard data. This resource uses all the available data on the project, however 30% of the assays from the now completed RC program are still outstanding and we have not yet started to test Esperança West or East," says Nick Appleyard, TriStar's President and CEO. "We are looking forward to updating the resource soon and completing the technical and economic studies that will support the preliminary economic assessment."
Table 1. Mineral resource estimate1 for the Castelo de Sonhos gold project (with an effective date of September 13, 2017) above a reporting cutoff2 of 0.4 g/t Au.
| Region | Resource Category | Tonnage (Mt) |
Grade (g/t Au) |
Metal Content3 (Moz Au) |
||||
| Esperança South | Inferred | 21 | 1.4 | 1.0 | ||||
| Esperança Center | Inferred | 10 | 0.9 | 0.3 | ||||
| Project Total | Inferred | 31 | 1.3 | 1.3 | ||||
| 1Numbers have been rounded to reflect the precision of an Inferred mineral resource estimate. 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. |
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As shown in Figure 1, the new resource estimate extends the footprint of the previous resource estimate considerably further to the southwest, and to the north. The new RC drilling also allows the resource block model to extend to 120m below surface, approximately 50m deeper than the previous block model. With the assays available by August 2017, resources were not estimated in gaps in Esperança South and Center where drill hole spacing exceeds 100m; and resources have not yet been estimated in Esperança East and West, where drilling is planned for 2018.
Figure 1. Map of the Castelo de Sonhos gold project, showing the gold soil anomaly (red-orange-yellow), the outcrop of the conglomeratic band (hatched), the footprint of the 2014 resource estimate (blue) and of the August 2017 resource estimate (green).
Resource estimation method
All available drill hole data was used, including the results from holes RC17-197 through RC17-249 that have not been published, but results are generally in line with previously disclosed drill results.
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.
Sample intervals were assigned one of three lithologies: pebble-supported conglomerate, matrix-supported conglomerate or "other". Ordinary kriging was used to estimate the proportion of each lithology within 30´30´6m panels; local uniform conditioning was used to estimate, for each lithology, the gold grade distributions of 5´5´2m selective mining units (SMUs) within each panel. The 5´5´2m SMU distribution of gold in each panel was a tonnage-weighted average of the distributions for each lithology. For each panel, the bedding direction was estimated from available surface measurements; ranges of correlation and search radiuses were set to 100m parallel to bedding, and 20m in Center and 30m in South perpendicular to bedding. Search strategy parameters were adjusted so that global grade-tonnage curves matched well to the results obtained from a change-of-support analysis of the distribution of composite gold grades in each area, Esperança South and Esperança Center, using a 5x5x2m block as the selective mining unit. This use of a target reference distribution from a global change-of-support analysis ensures that the estimates have the correct level of variability. The uniform conditioning block model was checked using a different grade estimation method, inverse-distance interpolation; the results of the two models are within ±10% of each other for the totals reported in Table 1.
Resource classification
All resources to a depth of 120m below the ground surface, inside the conglomerate band, and inside the green region shown in Figure 1 were classified as Inferred; no resources were classified as Measured or Indicated. Current open pit operations in similar paleo-placer projects such as the Tarkwa mine of Gold Fields show that resources down to 120m below surface have reasonable prospects for eventual economic extraction.
The resources classified as Indicated in 2014 have been reclassified as Inferred, pending implementation of CSA's recommendation for collection of a suite of samples for determination of dry bulk density.
Resource Sensitivity Table
Table 2. Mineral resource estimate sensitivity to cut-off for the Castelo de Sonhos gold project.
| Cut-off | Resource Category | Tonnage (Mt) |
Grade (g/t Au) |
Metal Content (Moz Au) |
||||
| 0.3 g/t | Inferred | 43 | 1.0 | 1.4 | ||||
| 0.5 g/t | Inferred | 24 | 1.5 | 1.2 | ||||
| 0.4 g/t | Inferred | 31 | 1.3 | 1.3 |
Qualified Person
Adrian Martinez (P.Geo.) of CSA Global is the independent Qualified Person for the mineral resource estimates presented in this press release, has approved its publication, and will be the principal QP for the National Instrument 43-101 technical report that will be filed on SEDAR within 45 days.
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.
