Riscos De Oro Project
Riscos de Oro Project
The 100% Calibre owned Riscos de Oro prospect is located in the Eastern Epithermal Camp of the Borosi concessions, 20 kilometers northeast of the historic mining town of Rosita. Riscos de Oro is a southwest trending, low sulphidation epithermal gold-silver quartz vein system that has been traced at surface for over 2 kilometres and has an inferred cumulative strike length of 7km. Rosario Resources operated a small scale open pit and underground mine here in the late 1970's which is reported to have produced 40,826 ounces of gold and 2,567,808 ounces of silver (Lehman, 1981). Several additional small mines were operated in this area by Rosario during the same time each exploited gold and silver from low-sulphidation style epithermal quartz veins. Borosi Concession Overview - Riscos de Oro |
 Diamond Drilling on Riscos de Oro Project 2011 |
A total of 37 diamond drill holes totaling 9,494 metres have been completed on Calibre's 100% owned Riscos de Oro project successfully outlining a continuously mineralized gold-silver zone 725 metres long and to a depth of 300 metres. The mineralized zone consists of one to three closely spaced sub-parallel vein structures each averaging between three to six metres in width. The majority of the 7.0 km long Riscos de Oro gold-silver trend remains open in all directions and largely untested by diamond drilling.
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 Updated Drill Map |
 Soil Anomlay Map |
 Cross Sections Map |
Inferred Resource at Riscos de Oro
The 2012 Riscos Mineral Resource estimate is based on 9494 metres in 37 diamond drill holes completed by Calibre in 2010 and 2011 as well as 22 existing drill holes totaling 3126.8 metres. The drilling is generally spaced at 25 to 50 metre intervals along strike and down dip. Additional data related to historical drilling, underground development and past production was used to aid in the geological interpretation.
The Riscos de Oro mineralized zone is a low sulphidation epithermal system consisting of two closely spaced zones of quartz veining, stockworks and breccias with associated sulphides. Limited past production occurred from a shallow open pit (now flooded) and two underground levels down to depth below surface of 91 metres previously accessed through a shaft in the late 1970's. No detailed records exist of this past production.
2012 Inferred Mineral Resource Summary
Zone |
Tonnes |
Grade (Au g/t) |
Grade (Ag g/t) |
Grade (AuEq g/t) |
Contained Au (ounces) |
Contained Ag (ounces) |
Contained (ounces AuEq) |
|---|---|---|---|---|---|---|---|
Upper |
1,539,000 |
2.45 |
64.42 |
3.46 |
121,200 |
3,188,000 |
|
Lower |
620,000 |
5.07 |
47.87 |
5.82 |
101,100 |
954,000 |
|
Total |
2,159,000 |
3.20 |
59.67 |
4.14 |
222,300 |
4,142,000 |
287,100 |
- CIM definition standards were followed for the resource estimate.
- The 2012 resource models used Inverse Distance grade estimation within a three-dimensional block model with mineralized zones defined by wireframed solids.
- A base cutoff grade of 0.6 g/t AuEq was used for reporting resources with capping of silver grades at 591 g/t.
- A density of 2.65 g/cm3 was applied.
- Numbers may not add exactly due to rounding.
- Gold Equivalent (AuEq) calculated using $1264 /oz Au for gold and $19.78/oz Ag for silver and metallurgical recoveries and net smelter returns are assumed to be 100%.
- Mineral Resources that are not mineral reserves do not have economic viability
- The quantity and grade of reported inferred resources in this estimation are uncertain in nature and there has been insufficient exploration to define these inferred resources as an indicated or measured mineral resource and it is uncertain if further exploration will result in upgrading them to an indicated or measured mineral resource category.
A summary of the inferred resource calculations for the Riscos de Oro deposit at different cutoff grades is summarized below:
The Resource Estimate also evaluated the Riscos de Oro Deposit at a range of cut off grades between 0.4 and 2.0 g/t AuEq. Results are as follows;
AuEq
CUT-OFF |
TONNES |
Grade
AuEq g/t |
Grade Au g/t |
Grade Ag g/t |
Contained Au oz |
Contained Ag oz |
Contained
AuEq oz |
|---|---|---|---|---|---|---|---|
0.4 |
2,255,000 |
3.98 |
3.08 |
57.56 |
223,290 |
4,173,423 |
288,599 |
0.6 |
2,159,000 |
4.14 |
3.20 |
59.67 |
222,257 |
4,142,076 |
287,075 |
0.8 |
2,037,000 |
4.34 |
3.36 |
62.41 |
220,309 |
4,087,071 |
284,266 |
1.0 |
1,917,000 |
4.56 |
3.53 |
65.27 |
217,797 |
4,023,009 |
280,752 |
1.2 |
1,807,000 |
4.77 |
3.70 |
68.17 |
214,918 |
3,960,356 |
276,893 |
1.4 |
1,696,000 |
4.99 |
3.88 |
71.41 |
211,325 |
3,893,867 |
272,259 |
1.6 |
1,595,000 |
5.21 |
4.05 |
74.62 |
207,545 |
3,826,497 |
267,425 |
1.8 |
1,514,000 |
5.40 |
4.19 |
77.55 |
203,963 |
3,774,633 |
263,032 |
2.0 |
1,451,000 |
5.55 |
4.31 |
79.59 |
201,016 |
3,713,150 |
259,122 |
 |
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Phase I and II Drilling Results
Beginning in late 2009, Calibre completed reconnaissance geological mapping over a 20 square kilometer area, excavated 87 metres of trenches and collected 106 surface rock and 1,393 soil samples. In 2010 and 2011, 4,600 metres of diamond drilling in 18 holes was completed by Calibre at Riscos de Oro.
The historically defined ore shoot at Riscos de Oro was only mined to an approximate depth of 93 metres below surface and along strike for 300 metres. The initial drill program in 2010 focused on testing the down dip extension of the known mineralization and tested for an additional possible ore shoot along strike of the main workings towards the northeast. Over the course of the initial program, Calibre was able to extend the historically exploited ore shoot to a depth of over 280 metres, highlighted by intercepts of 11.50 g/t gold and 72.30 g/t silver over 2.30 metres (RD10-003) and 2.44 g/t gold and 292.60 g/t silver over 5.80 metres (RD10-001).
As part of the same program, drill-hole RD10-005 was collared approximately 300 metres along strike and to the northeast of hole RD10-001. RD10-005 intercepted 9.04 g/t gold and 30.02 g/t silver over 4.14 metres. This hole was noteworthy as it confirmed that Riscos de Oro is a robust gold-silver target with numerous mineralized ore shoots that can be traced on surface and to depth below shallow historic workings. This hole was followed up by RD10-009 which intercepted 4.23 g/t gold and 384.86 g/t silver over 8.53 metres.
The 2011 drilling program was designed to follow up on the multiple high grade gold and silver intercepts from 2010. The 2011 program was extremely successful with the majority of the 29 diamond drill holes totaling 4,867.2 metres intersecting significant widths and grades of gold-silver mineralization further confirming the extensive and robust nature of this precious metal epithermal system. In addition, economically significant parallel epithermal veins were encountered beneath the historically defined veins significantly adding to the potential of the system. The 2011 program was highlighted by drill-hole RD11-010 which intercepted 10.25 g/t gold and 288.25 g/t silver over 5.40 metres and RD11-017 which intercepted 9.31 g/t gold and 336.06 g/t silver over 3.90 metres. Additional holes from the 2011 Phase II of drilling include RD11-021 which intercepted 4.4 g/t gold and 24.12 g/t silver over 8.64 metres and RD11-037 which intercepted 8.66 g/t gold and 37.57 g/t silver over 4.21 metres. In addition, economically significant parallel epithermal veins were encountered beneath the historically defined veins significantly adding to the potential of the system. The 2011 program was highlighted by drill-hole RD11-010 which intercepted 10.25 g/t gold and 288.25 g/t silver over 5.40 metres and RD11-017 which intercepted 9.31 g/t gold and 336.06 g/t silver over 3.90 metres.
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 Riscos de Oro Drill Hole RD10-005 |
 Riscos de Oro Drill Hole RD11-011 |
 Riscos de Oro Drill Hole RD11-011 |
 Riscos de Oro Drill Hole RD11-015 |
 Riscos de Oro Drill Hole RD11-015 |
 Riscos de Oro Drill Hole RD11-016 |
Highlights of the assay results for the completed programs in 2010 and 2011 are compiled below.
| Hole ID | From (m) |
To (m) |
Interval (m) |
Gold (g/t ) |
Silver (g/t) |
|---|---|---|---|---|---|
| RD10-001 | 177.60 | 183.40 | 5.80 | 2.44 | 292.60 |
| including | 177.60 | 178.40 | 0.80 | 14.05 | 1,990.00 |
| RD10-009 | 160.70 | 169.23 | 8.53 | 4.23 | 384.86 |
| RD11-010 | 167.1 | 168.6 | 1.50 | 5.98 | 9.10 |
| and | 187.4 | 191.6 | 4.20 | 2.50 | 5.16 |
| and | 223.0 | 228.4 | 5.40 | 10.25 | 288.25 |
| including | 224.5 | 226.5 | 2.00 | 24.00 | 714.25 |
| RD11-012 | 249.30 | 259.90 | 10.60 | 7.69 | 211.87 |
| including | 249.30 | 255.95 | 6.65 | 9.16 | 252.50 |
| and | 257.90 | 259.90 | 2.00 | 10.02 | 268.00 |
| RD11-015 | 182.00 | 184.20 | 2.20 | 5.44 | 405.55 |
| RD11-016 | 198.50 | 205.60 | 7.10 | 2.72 | 287.65 |
| including | 201.92 | 205.60 | 3.68 | 3.61 | 518.44 |
| and | 249.42 | 253.71 | 4.29 | 3.20 | 13.30 |
| including | 249.42 | 250.42 | 1.00 | 12.35 | 47.00 |
Click here to view complete assay results for the completed programs in 2010 and 2011 in PDF Format
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 Riscos de Oro 2011 Drill Plan |
 Riscos de Oro Section Plan A to A' |
 Riscos de Oro RD11-016 cross section |
 Riscos de Oro RD11-017 cross section |
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 Riscos de Oro Longitudinal Section |
 Riscos de Oro Drill Hole Locations |
 Riscos de Oro Section with RD10-003 |
 Riscos de Oro Section with RD10-009 |
Geology
Historically defined mineralization occurs within a single epithermal quartz vein zone that ranges from 7 to 11 metres thick in underground workings, strikes 053o and dips 60o towards the northwest. The vein is commonly of low sulphide content (~3%) but can locally contain up to 10% sulphides. The observed sulphide assemblage includes pyrite, chalcopyrite, sphalerite, galena and argentite.
The low-sulphidation epithermal veins encountered in the northeastern part of the Borosi concessions (of which Riscos de Oro is included) are similar in many respects to the epithermal veins of the >2.6 million ounce Bonanza gold-mine district, located 35 kilometres to the west. The areas of defined veining in each camp are roughly similar in size (12 x 14 km for the northeast Borosi concessions; 7 x 20 km for Bonanza), both are hosted by Cretaceous to mid-Tertiary Matagalpa and pre-Matagalpa Formation andesitic volcanic rocks, the majority of veining strikes NE-SW and dips steeply towards the northwest and the veins appear related to Tertiary extension in northeastern Nicaragua. Topographic relief in the Bonanza camp is significant and therefore delineation of epithermal veins is easier than on the Borosi concessions were the topography is more subdued.