By Sunridge Gold,
Sunridge Gold Corp. has now received the final resource estimate update for the Gupo gold deposit, the fourth deposit that forms the basis of the Asmara North Prefeasibility Study.
The Asmara North deposits include the Emba Derho volcanogenic-massive-sulphide (VMS) copper-zinc-gold deposit, the Adi Nefas zinc-gold-copper VMS deposit and the Gupo gold deposit. The Prefeasibility Feasibility study is also considering the possibility of processing ore from the Debarwa copper-zinc-gold VMS deposit at a centralized mill near the Emba Derho deposit (see map below).
The study is expected to be complete later this month.
“All four deposits on Sunridge’s Asmara Project now have updated NI43-101 compliant resource estimates completed as part of the current Prefeasibility Study on the Asmara North and the Feasibility Study on Debarwa,” stated Michael Hopley, Sunridge President and CEO. “We expect that most of these resources will be converted to reserves in the Preliminary Feasibility Study and management looks forward to a very positive study.”
|Contained Metal in Measured and Indicated Resources – Asmara Projects|
|Zone||Copper million lbs||Zinc million lbs||Gold thousand oz||Silver million oz|
|Asmara North Projects|
|Emba Derho||Gold Oxide||–||–||59.00||0.24|
|Gupo Gold||Oxide and Primary Horizons||–||–||47.00||–|
|Sub-total Asmara North||1,066.00||2,479.00||749.00||25.43|
|Total Asmara Projects||1,265.85||2,553.05||930.00||28.36|
Note: Contained metal calculations are as follows: copper and zinc: tonnes x grade (%) x 2204.622. Gold and silver: tonnes x grade (g/t) ÷ 31.10348. Results were rounded and no allowance was made for mining dilution or metal losses in the recovery process.
|Measured and Indicated Resources – Asmara Projects|
|Zone||Cut-off grade||Million tonnes||Copper %||Zinc %||Gold g/t||Silver g/t|
|Asmara North Projects|
|Emba Derho||Gold Oxide||0.5 g/t Au||1.74||0.07||0.04||1.06||4.30|
|Copper Supergene||0.5% Cu||1.64||0.94||0.38||0.17||12.20|
|Copper-rich Primary||0.3% Cu||49.80||0.83||0.93||0.17||7.70|
|Zinc-rich Primary||<0.3% Cu/>1% Zn||16.80||0.14||2.80||0.31||9.90|
|Adi Nefas||Primary||2.0% Zn||1.84||1.78||10.05||3.31||115.00|
|Gupo Gold||Oxide and Primary Horizons||0.5 g/t Au||0.95||–||–||1.53||–|
|Sub-total Asmara North||72.77|
|Debarwa||Oxide||0.5 g/t Au||0.37||0.06||0.04||1.47||6.00|
|Transition||0.5 g/t Au||0.72||0.08||0.05||2.85||27.00|
|Primary (Cu)||0.5% Cu||0.77||2.34||3.92||1.30||29.00|
|Primary (Zn)||2.0% Zn||0.06||0.36||3.05||1.24||22.00|
|Total Asmara Projects||76.09|
Note: The Debarwa resource was announced on August 18, 2011, the Emba Derho resource was announced on February 6, 2012, the Adi Nefas resource was announced on February 22, 2012 and the Gupo resource update is included in this release.
GUPO GOLD RESOURCE UPDATE
Gupo is the smallest of the four deposits on the Asmara Project and is being examined in the prefeasibility study as a possible source of feed for a centralized gold recovery plant that would include the gold caps from the Emba Derho and Debarwa deposits. The new resource at Gupo is summarized as follows:
Gupo Gold Deposit Indicated Resources
|Cut-off Grade g/t gold||Tonnes||Avg. Grade g/t Au||Ounces of gold|
Gupo Gold Deposit Inferred Resources
|Cut-off Grade g/t gold||Tonnes||Avg. Grade g/t Au||Ounces of gold|
Gold mineralization at Gupo extends intermittently over a strike length of approximately 1.6 kilometres and is associated with stockwork quartz veins and a sericite alteration halo controlled by a shear zone 10 to 30 metres in width. The deposit crops out at surface where there are several shallow pits resulting from artisanal mining during the Italian colonial period. Drilling by Sunridge has shown mineralization to extend up to 150 metres vertically from surface and in many locations is open to depth.
This new Gupo resource estimate, completed by Snowden, is as of April 3, 2012, and complies with the CIM Definition Standards on Mineral Resources and Mineral Reserves, as required by National Instrument 43-101. Resource modeling and grade estimation was undertaken by Snowden and reviewed by Andrew F. Ross, FAusIMM (CP Geo), P.Geo. (APEGBC #145711) (Senior Principal, Snowden), a Qualified Person as defined by NI 43-101, based on geological interpretations and a drill database (current to January 2012) provided by Sunridge. The database and the Sunridge sampling and assaying QA/QC procedures and results were reviewed by Snowden. Further details of the estimation procedure will be available in the NI-43-101 report which will be posted on the Company’s profile on SEDAR (http://www.sedar.com) no later than 45 days from the date of this press release.
GUPO GEOLOGICAL BACKGROUND
The Gupo deposit is shear controlled gold deposit hosted by a series of pillow lavas, felsic pyroclastics, and sediments cut by quartz porphyry and quartz veins. The shears are oriented at 015° and dip 80° east. The mineralization is made up of quartz-feldspar-carbonate-sericite-pyrite-gold hydrothermal alteration in a 200 to 300 metre wide band that is double the width of the associated shear zone. The mineralization extends along strike for a distance of 1.6 kilometres with the gold mineralization trend starting nine hundred metres south of the Adi Nefas gossan which overlies the Adi Nefas base metal occurrence. The deposit is partitioned into a near-surface upper Oxide horizon ranging in thickness from 20 metres to 40 metres and a pyritic (Primary) horizon extending approximately 50 metres below the Oxide horizon. The Oxide horizon has typically low sulphide content (approximately 0.8% pyrite). The Primary horizon has a typical pyrite content of 1.5% pyrite. Metallurgical testwork indicates overall gold recovery of approximately 95%.
Drilling has defined two mineralized zones separated along strike by a distance of one kilometre. Each zone is made up of irregular sub-zones with the north zone having a separate, thinner, sub-zone running sub-parallel to it 90 metres to the west. The north and south zones are separated by a 720 metre barren zone.
The mineralization on which the Gupo resource estimate is based extends over a strike length of 1.6 kilometres and a width of up to 60 metres and has been drilled to a maximum vertical depth from surface of approximately 175 metres. The resource has been estimated using 176 exploration drill holes consisting of 18 diamond drill core holes and 158 reverse circulation drill holes. Assays of split core and reverse circulation samples have been used in this estimation of resources.
The interpretations of mineralized zones as 0.1 g/t gold grade shells were modeled using three-dimensional wireframing techniques based on a distribution of drill intersections ranging from less than 15 metre to up to 135 metre spacings on 20 metre drill section intervals. The wireframe interpretations formed the basis for the construction of a block model as well as the constraining of samples for geostatistical analysis and grade estimation. A block model was constructed in Vulcan mining software with a parent cell dimension of 15 metre (X) x 15 metre (Y) x 5 metre (Z) subcelled to 5 metre x 5 metre x 2.5 metre (XYZ) for accurate coding with the wireframe interpretations and surface topography.
Grades for gold were estimated within grade shells using Ordinary Kriging after compositing the assay intervals to 1.0 m down-hole lengths within the mineralized shell contacts. Search ellipsoid dimensions and orientations were determined on structural geological and geostatistical information. Density (specific gravity) values of 2.70 and 2.80 for oxide and primary horizons respectively were assigned to blocks based on 171 density measurements provided by Sunridge.
The interpreted mineralized zones were categorized for resource classification as Indicated or Inferred in a series of steps. Each zone was reviewed in the context of the spatial distribution of drill intersections used to model and estimate grades for that zone, with due consideration for the known geological and geostatistical continuities and confidences in the base data and geological interpretations. On this basis the relatively densely drilled (20 metre section spacing) north zone received Indicated status where geological continuity could be demonstrated. All other areas with less drill density were classified as Inferred.
Mineral Resource estimates reported for Gupo are constrained by a conceptual pit shell in order to determine the potential quantity for eventual economic extraction. Parameters used in the generation of the Whittle pit shell are: gold price = $US2,300/ounce; mining cost = $2.10/tonne; processing cost (including administration cost) = $US28.48/tonne; recovery = 92% (oxide) 93.4% (primary); pit slope angle = 45 degrees. CIM Definition Standards describe that Mineral Estimates are not Mineral Reserves and do not have demonstrated economic viability. There is no certainty that all or any part of the Mineral Resource will be converted into Mineral Reserve until the required studies have been completed.
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