Rockhaven Resources Ltd. (TSXV:RK) (“Rockhaven”) is pleased to announce updated Mineral Resource estimates for the high-grade Western BRX, Central BRX, Central Klaza, and Western Klaza zones at its 100%-owned and road accessible Klaza property, located in the Dawson Range Gold Belt of southern Yukon.
The updated Mineral Resource estimates incorporate results from approximately 13,300 m of in-fill and expansion diamond drilling completed subsequent to the 2015 Mineral Resource estimate, and utilizes results from recent metallurgical test work to revise cut-off grades. Bulk tonnage low-grade mineralization in the Eastern Zones requires additional sampling, drilling and modeling, and is not included in these Mineral Resource estimates.
Highlights from this news release include:
- Indicated Mineral Resources of 4.5 Mt containing 686,000 oz gold and 14,071,000 oz silver (grading 4.8 g/t gold and 98 g/t silver) or 907,000 oz gold equivalent (grading 6.3 g/t gold equivalent);
- Inferred Mineral Resources of 5.7 Mt containing 507,000 oz gold and 13,901,000 oz silver (grading 2.8 g/t gold and 76 g/t silver) or 725,000 oz gold equivalent (grading 3.9 g/t gold equivalent); and,
- Pit-constrained resources significantly increased in tonnes and grade compared to previous Mineral Resource estimates, including the Western BRX Zone with 759 kt at an average grade of 9.5 g/t gold, totaling 232,000 oz gold in the Indicated category.
Table 1: Mineral Resource Estimate Summary, June 5, 20181,5
| Tonnes | Grade | Contained Metal | |||||||||
| Au | Ag | Pb | Zn | AuEQ4 | Au | Ag | Pb | Zn | AuEQ4 | ||
| (kt) | (g/t) | (g/t) | (%) | (%) | (g/t) | (koz) | (koz) | (klb) | (klb) | (koz) | |
| Indicated3 | 4,457 | 4.8 | 98 | 0.7 | 0.9 | 6.3 | 686 | 14,071 | 73,268 | 92,107 | 907 |
| Inferred3 | 5,714 | 2.8 | 76 | 0.6 | 0.7 | 3.9 | 507 | 13,901 | 77,544 | 89,176 | 725 |
1 CIM Definition Standards (2014) were used for reporting the Mineral Resources. Using drilling results to December 31, 2017. The Qualified Persons are Adrienne Ross, P.Geo. of AMC Mining Consultants (Canada) Ltd, and Nicholas Ingvar Kirchner, FAusIMM, MAIG. of AMC Mining Consultants Pty Ltd.
2 Near surface Mineral Resources are constrained by an optimized pit shell at a metal prices of $1,400/oz Au, $19/oz Ag, $1.10/lb Pb, and $1.25/lb Zn.
3 Cut-off grades applied to the pit-constrained and underground resource are 1.0 g/t and 2.3 g/t AuEQ respectively.
4 Gold equivalent values assume $1,400/oz Au, $19/oz Ag, $1.10/lb Pb, and $1.25/lb Zn, and variable recoveries for the different metals.
5 Numbers may not add up due to rounding. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. All metal prices are quoted in US$ at an exchange rate of $0.80 US to $1.00 Canadian.
“The Klaza project hosts high-grade gold and silver resources that are near surface, road accessible and located within one of the safest mining jurisdictions in the world,” stated Matt Turner, CEO of Rockhaven Resources. “We have upgraded much of our Inferred Mineral Resource to the Indicated category for $4 per oz gold or at a rate of 52 oz gold per metre drilled.* Additionally, the conversion of high-grade resources from underground to open pittable should have major economic benefits for the project.”
The following table reports the Mineral Resources by potential mining method.
Table 2: Mineral Resource Estimate by mining method, June 5, 20181,5
|
Category |
Tonnes | Grade | Contained Metal | ||||||||
| Au | Ag | Pb | Zn | AuEQ4 | Au | Ag | Pb | Zn | AuEQ4 | ||
| (kt) | (g/t) | (g/t) | (%) | (%) | (g/t) | (koz) | (koz) | (klb) | (klb) | (koz) | |
| Indicated | |||||||||||
| Pit-Constrained2,3 | 2,447 | 5.3 | 90 | 0.7 | 1.0 | 6.7 | 414 | 7,096 | 39,143 | 52,935 | 529 |
| Underground3 | 2,010 | 4.2 | 108 | 0.8 | 0.9 | 5.8 | 272 | 6,974 | 34,125 | 39,172 | 378 |
| Total | 4,457 | 4.8 | 98 | 0.7 | 0.9 | 6.3 | 686 | 14,071 | 73,268 | 92,107 | 907 |
| Inferred | |||||||||||
| Pit-Constrained2,3 | 1,754 | 2.6 | 43 | 0.4 | 0.5 | 3.3 | 147 | 2,429 | 14,897 | 18,599 | 187 |
| Underground3 | 3,960 | 2.8 | 90 | 0.7 | 0.8 | 4.2 | 359 | 11,472 | 62,647 | 70,578 | 538 |
| Total | 5,714 | 2.8 | 76 | 0.6 | 0.7 | 3.9 | 507 | 13,901 | 77,544 | 89,176 | 725 |
* See footnotes under Table 1
About the Klaza Deposit
The Klaza project hosts a large hydrothermal system that is concentrated within a 4 km long by 3 km wide structural corridor. Current Mineral Resource areas have only been systematically explored to about 275 m below surface, but well mineralized intersections occur as deep as 450 m. Eleven known mineralized zones have been identified within the corridor and all are open for expansion along strike and to depth. The deposit model for the Klaza deposit suggest the zones could be well mineralized to depths of 1,000 m or more below surface.
In spring 2016, Rockhaven completed a Preliminary Economic Assessment (PEA) of the Klaza property in order to demonstrate project viability and recognize key economic sensitivities. The PEA identified several opportunities to improve future economics, including:
- Exploring alternate processing methods that could lower overall processing costs and allow lower-grade mineralization, which was excluded from the PEA, to be effectively processed;
- Better definition of near surface mineralization in order to maximize the open-pit potential of the Mineral Resources; and,
- Infill drilling in order to confirm grade continuity within the deposit and increase the grade of the known high-grade veins.
In 2016 and 2017, Rockhaven completed 13,291 m of infill and expansion diamond drilling, within and near to the 2015 Mineral Resources. This drilling successfully demonstrated the continuity of high-grade structures and identified much higher-grade areas within the known vein zones. Examples of these high-grade intersections include 182 g/t gold and 231 g/t silver over 0.61 m in Central Klaza; and, 94 g/t gold and 545 g/t silver over 2.63 m in Western BRX. The drilling also outlined lower-grade mineralization in the hanging wall and footwall of the Central Klaza Zone, and provided material for metallurgical testing.
The eastern portion of the Klaza vein system (Eastern Zones) comprises multiple, sub-parallel veins and veinlets, and includes the Eastern Klaza, Eastern BRX, Pika, Stroshein, and part of the AEX zones. All of these zones are open to the east, towards the mostly untested Kelly Porphyry. Previously, these zones were assumed to be similar to the discreet high-grade vein zones to the west (Western and Central portions of the BRX and Klaza) and were sampled, targeted and modeled using this assumption. The recent drilling and metallurgical test work have demonstrated that the mineralization is structurally, mineralogically and metallurgically different from the western zones. This area has bulk tonnage potential and requires additional sampling, drilling and modelling before a Mineral Resource estimate can be finalized.
Metallurgical testwork completed in 2017 demonstrates that dense media separation is effective in the Central Klaza, Western BRX, and Eastern zones (see Rockhaven news release dated April 19, 2018). This test work also showed that the Eastern Zones responded well to direct cyanide leaching. The new processing techniques identified by the test work allow for lower cut-off grades to be applied to the current Mineral Resource estimates. The application of pre-concentration should allow for less selective, lower cost mining methods in both …read more
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