Rio Alto Provides La Arena Project Update and San Andres Drilling Results
March 14 2011 - 8:58AM
Marketwired
Rio Alto Mining Limited ("Rio Alto" or the "Company") (TSX VENTURE:
RIO)(OTCQX: RIOAF)(BVLAC: RIO)(DBFrankfurt: MS2) is pleased to
provide a La Arena Project update and report assay results from 16
drill holes at the newly discovered San Andres oxide gold target
located adjacent to the recently completed leach pad at the La
Arena Gold Oxide Mine ("Oxide Mine") located in Peru.
Development work at the Oxide Mine is complete and construction
of the process plant and camp facilities is being finished. To-date
a 14 hectare leach pad and a 57,500 cubic meter pregnant leach
solution pond are finished. Commissioning of the
adsorption/desorption and electro winning plant will begin this
month in preparation for gold production. A 300 man camp, offices
and associated infrastructure will be completed in April.
The San Andres zone was identified as part of the Company's
recently initiated 12,000m reverse circulation drilling program
focused on expanding oxide gold mineralization in and around the
current La Arena gold oxide resource. San Andres is a gold oxide,
brecciated sandstone zone of mineralization located along strike
and to the north of the La Arena gold oxide resource. As the San
Andres zone is constrained by its location between the pad and the
PLS pond, Rio Alto will not drill this zone to define a resource,
but will deliver mineralized material from San Andres to the leach
pad after evaluating blast hole sample results and as permitted by
the mine plan.
Significant intercepts from these drill holes are highlighted
below. An economic cut-off grade of 0.11 g/t in gold oxides was
established by independent engineers, Coffey Mining Pty Ltd, in the
NI 43-101 study dated July 31, 2010.
-- 58m @ 0.5g/t Au, 4.4g/t Ag in hole SA-R11-006
-- 42m @ 1.08g/t Au, 0.4g/t Ag in hole SA-R11-013
-- 60m @ 0.4g/t Au, 0.52g/t Ag including 28m @ 0.62g/t Au, 0.46g/t Ag in
hole SA-R11-015
Alex Black, President and COO of Rio Alto, commented, "We are
pleased with this first phase drilling success at La Arena, which
supports our belief in the excellent potential to expand the
mineral resources on the property. The drilling has identified
mineralization beyond the current resources and reserves. The
12,000 metre reverse circulation gold oxide exploration program for
2011 is in progress and we expect future results will continue to
demonstrate the growth potential of this project."
Summary of Results
The San Andres zone is situated to the north east of the Ethel
breccia. Two layers of highly oxidized breccia sandstone outcrop at
surface in the area. Geologically, gold mineralization is
associated within highly fractured and oxidized sandstone rocks
similar to La Arena's Calaorco and Ethel gold oxide deposits. The
sandstone bedding at San Andres dips gently to the south east and
the mineralization is controlled by this feature. Two layers of
mineralization, one 40 metres thick and the other 100 m thick, have
been identified. A recent geochemical survey identified gold
anomalism similar to the Calaorco and Ethel resources located at La
Arena. Based on the geological and geochemical results a reverse
circulation drilling program comprising 2811 metres within 16 holes
was completed. In total 11 holes encountered mineralization above
the economic cutoff.
Hole ID From To Length Au g/t Ag g/t
SA 01 24 32 8 0.30 0.38
SA 01 60 66 6 0.27 0.20
SA 01 200 224 24 0.33 0.58
SA 02 6 24 18 0.28 0.21
SA 02 50 58 8 0.39 0.20
SA 02 140 144 4 0.28 0.70
SA 03 22 54 32 0.23 0.22
SA 04 0 44 44 0.37 0.28
SA 04 130 136 6 0.39 0.63
SA 05 6 12 6 0.27 0.20
SA 05 66 148 82 0.21 0.45
Including 66 78 12 0.35 0.25
SA 06 184 242 58 0.50 4.24
SA 09 8 22 14 0.24 0.20
SA 10 44 52 8 0.25 4.50
SA 11 36 48 12 0.20 0.27
SA 11 80 98 18 0.24 1.54
SA 13 0 8 8 0.27 0.20
SA 13 28 70 42 1.08 0.40
SA 13 180 250 70 0.29 0.92
SA 15 26 86 60 0.40 0.52
Including 58 86 28 0.62 0.46
Quality Control and Assurance
Sampling of the reverse circulation drilling and sample
preparation were performed by Rio Alto personnel; and were carried
out under strict protocols recommended in the NI 43-101 Technical
Report dated July 31, 2010 prepared by Coffey Mining Pty Ltd.
Samples were taken every 2m and split in half to yield seven to ten
kilogram samples. Drill sample recovery was generally in excess of
90%. Rio Alto has a rigorous QA/QC program to control the
chain-of-custody of samples and the insertion of blanks,
duplicates, and certified reference standards in each batch of
samples. Samples were shipped to CIMM-Peru in Lima where they were
dried, crushed, pulverized, and assayed. All gold assays were
obtained by standard 50g fire assaying with AA finish. All silver
assays reported in the press release were obtained by Aqua-Regia
dissolution followed by ICP measurement. CIMM-Peru is an ISO
9001:2000 certified laboratory.
Enrique Garay, M Sc. P. Geo. (AIG Member), Vice President
Geology of Rio Alto is the Qualified Person responsible for the
management of the exploration program and disclosure of the drill
results as defined by National Instrument 43-101. Mr. Garay has
reviewed and verified the technical and scientific information in
this news release.
This news release contains certain forward-looking information
including statements concerning the expected timing for completion
of a gold recovery plant and production of gold. All statements
included herein, other than statements of historical fact, are
forward-looking information and such information involves various
risks and uncertainties. There can be no assurance that such
information will prove to be accurate, and actual results and
future events could differ materially from those anticipated in
such information. A description of assumptions used to develop such
forward-looking information and a description of risk factors that
may cause actual results to differ materially from forward-looking
information can be found in Rio Alto's disclosure documents on the
SEDAR website at www.sedar.com. Rio Alto does not undertake to
update any forward-looking information except in accordance with
applicable securities laws.
To learn more about Rio Alto Mining Limited, please visit:
www.rioaltomining.com or Rio Alto's SEDAR profile at
www.sedar.com.
ON BEHALF OF THE BOARD OF RIO ALTO MINING LIMITED
Alex Black, President & COO
Neither TSX Venture Exchange nor its Regulation Services
Provider (as that term is defined in the policies of the TSX
Venture Exchange) accepts the responsibility for the adequacy or
accuracy of this release.
Contacts: Rio Alto Mining Limited Alex Black President & COO
+51 1 625 9900 or +51 99279 4655 alexb@rioaltomining.com Rio Alto
Mining Limited Alejandra Gomez Investor Relations +1 604 628 1401
+1 866 393 4493 (FAX) alejandrag@rioaltomining.com
www.rioaltomining.com
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