Castelo de Sonhos Gold Project
The Deposit
The Castelo de Sonhos gold project is situated in the Pará state of Brazil, approximately 20km from the town of Castelo de Sonhos. It is a paleoplacer gold deposit that is large, simple and in the right location.
Key Attributes
- Substantial amounts of untested growth potential
- Robust Preliminary Economic Assessment
- Mineralization at surface → simple open pit
- Good metallurgical properties → high gold recovery
- Connected to grid power, close to highway → good infrastructure
Preliminary Economic Assessment results in November 2018 indicate pre-tax IRR of 51% at a gold price of US$1250, with a low-cost base and strong leverage for higher gold prices.
Key Economic Parameters
|
Parameter |
Unit |
Pre-tax |
Post-tax |
|
Cash Flow |
US$ millions |
441 |
372 |
|
IRR |
% |
51 |
43 |
|
NPV 5% |
US$ millions |
319 |
264 |
|
NPV 10% |
US$ millions |
233 |
188 |
|
Cash Cost |
US$/oz |
660 |
|
|
AISC |
US$/oz |
687 |
|
|
Initial Capital |
US$ millions |
184 |
|
|
Life of Mine Production |
Moz gold |
1.1 |
|
|
Average Annual Production |
oz gold |
130,000 |
|
|
Payback Period (Mine Life) |
years |
1.9 (of 8.1 years) |
Details are reported in press release dated Nov 16, 2018 titled '51% IRR from PEA at TriStar Gold’s Castelo de Sonhos Project’
The QP taking responsibility for this work is of the opinion that the information remains relevant and current despite the fact that it pre-dates the current resource estimate. Work is already underway on the Pre-Feasibility Study (PFS) for Castelo de Sonhos; the technical and economic analysis presented in the PFS will be based on new resource estimates, will not assign any economic value to Inferred resources, and, when published, will entirely replace the PEA analysis.
The PEA is preliminary in nature and includes Inferred Mineral Resources that are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as Mineral Reserves. There is no certainty that the economic results described in the PEA will be realized. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.
Estimated All In Sustaining Costs per ounce of gold produced is a Non-GAAP measure that is equal the total of site mining costs, site and corporate G&A costs, royalties and production taxes, realized gains/losses on hedging transactions, community and permitting costs relating to current operations, refining costs, site based non-cash remuneration, inventory write-downs, stripping costs, byproduct credits, reclamation costs, and sustaining costs related to exploration and studies, capital exploration, capitalized stripping and underground mine development, and capital expenditures, divided by the estimated total ounces of gold produced during the life of the mine.
Current Resource
The project currently has mineral resources of:
Indicated: 40.1 million tonnes at 1.2 g/t, containing 1.5 million ounces ("Moz") of gold.
Inferred: 22.2 million tonnes at 1.0 g/t, containing 0.7 Moz of gold.
| Region | Classification | Tonnage (Mt) |
Grade (g/t Au) |
Metal Content3 (Moz Au) |
|---|---|---|---|---|
| Esperança South | Indicated | 24.5 | 1.3 | 1.1 |
| Inferred | 10.4 | 1.1 | 0.4 | |
| Esperança East | Indicated | 2.4 | 1.1 | 0.1 |
| Inferred | 9.4 | 0.9 | 0.3 | |
| Esperança Center | Indicated | 13.1 | 0.8 | 0.3 |
| Inferred | 2.4 | 0.9 | 0.1 | |
| Project Total | Indicated | 40.1 | 1.2 | 1.5 |
| Inferred | 22.2 | 1.0 | 0.7 |
1Project totals may appear not to sum correctly since all numbers have been rounded to reflect the precision of Inferred and Indicated mineral resource estimates.
2The reporting cutoff corresponds to the marginal cutoff grade for an open pit with processing + G&A cost of $US 12/t, metallurgical recovery of 98% and a gold price of $US 1,250/oz. To meet the requirement of "reasonable prospect for eventual economic extraction" the mineral resources must also fall within a bounding pit shell with 55° walls. 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.
Details are reported in press release dated March 16, 2021 titled 'TriStar Doubles Indicated Resources as Drilling Continues at Castelo de Sonhos'
Geology and Mineralization
The Castelo de Sonhos property encompasses a 15km by 12km plateau in the Tapajós region of Pará state. It has an average elevation above sea level of approximately 600m and stands around 350m above the surrounding plains.
The Castelo de Sonhos Formation is a package of sandstones and conglomerates which form a roughly circular plateau surrounded by intrusive granites of the Tapajós-Parima Province.
The gold mineralization is generally associated with the conglomerate reefs. The main alteration types are hematite and silicification, although these are not believed to be directly linked to the deposition of the gold in the conglomerates.
Analogous Deposits
| TARKWA | JACOBINA | CASTELO DE SONHOS | |
|---|---|---|---|
| Location | Ghana | Brazil | Brazil |
| Age (Ga) | 2.1 | 1.88 ─ 2.09 | 2.1 |
| Total Deposit (Moz Au) | ~30 Moz Au | ~10 Moz Au | tbd |
| Mine Type | Open Pit & Underground | Open Pit & Underground | Initially Open Pit |
| Grade | 1.2 g/t (pit) | 1.9 g/t (pit) | 1.45 g/t (PEA) |
| Underground Grade | > 6 g/t | 2.5 ─ 9.5 g/t | - |
| Thickness of Mineralized Zones | ≤ 8 m | ≤ 25m | ≤ 20m |
| Host Rock | Quartzites and pebble conglomerates | Quartzites and pebble conglomerates | Quartzites and pebble conglomerates |
Two billion years ago, a large continent lay near the South Pole, with a chain of lode gold deposits along its central mountain ridge. Gold accumulated in placer deposits down-slope, in alluvial fans, on beaches and in the near-shore marine environment. In modern times, these now include gold deposits at Tarkwa, Jacobina and Castelo de Sonhos.
Technical Report
