Mariana Resources Ltd.: Further Zones of Volcaniclastic-Hosted Gold-Silver Mineralisation at Las Calandrias Project, Argentina

VANCOUVER, BRITISH COLUMBIA -- (Marketwire) -- 08/07/12 -- Mariana Resources Ltd (TSX: MRY)(AIM: MARL) ('Mariana' or 'the Company'), the AIM and TSX quoted exploration and development company focused in southern Argentina and Chile, is pleased to announce positive results from re-sampling drill hole core from its Las Calandrias gold-silver project ('Las Calandrias') located in the world class Santa Cruz Gold Province in southern Argentina (see Figure 1). Re-sampling was prompted by positive results from the last drilling campaign which discovered disseminated and veinlet/stockwork style gold mineralisation hosted by volcaniclastic rocks outside the rhyolite-hosted resource areas at Calandria Sur.

Overview

--  Results for re-sampling of the second batch of 33 previous drill holes
    (see Figure 2), returned gold intersections in 26 holes
--  Best intersections in volcaniclastic rocks on the Eastern Border of the
    main Calandria Sur rhyolite hosted resource:
    --  11.0m @ 0.5 g/t gold (Au), 5 g/t silver (Ag) from 80.5m - CSD28
    --  24.5m @ 0.8 g/t Au, 12 g/t Ag from 83.5m - CSD103
    --  7.0m @ 0.8 g/t Au from 18m - CSD262
    --  7.0m @ 0.8 g/t Au from 6m - CSD278
--  Best intersections hosted by volcaniclastic rocks below the base of the
    Calandria Sur rhyolite dome:
    --  23m @ 0.5 g/t Au 5g/t Ag from 92m - CSD33
    --  27m @ 1.0 g/t Au 13 g/t Ag from 89m - CSD105
    --  9.5m @ 1.2 g/t Au 19 g/t Ag from 113m - CSD106
    --  13m @ 0.7g/t Au 5 g/t Ag from 85m - CSD107
    --  15m @ 0.7 g/t Au from 65m - CSD111
--  Additional sampling of hole CSD222 returned 1m @ 2.7 g/t Au and 114 g/t
    Ag from 217m, below previously released intersections of 3m @ 2.4 g/t Au
    & 12 g/t Ag from 147m and 6m @ 1.7 g/t Au & 17 g/t Ag from 207m
--  LeachWell assays show higher than expected gold extractions for primary
    volcaniclastic-hosted mineralisation on the Eastern (80%) and Western
    (89%) Borders of Calandria Sur
--  Results for the recently completed 21-hole (2,164m) diamond drill
    programme outside of the Calandria Sur initial resource area are
    expected this month.

Commenting today, Chairman John Horsburgh said, "The second batch of results of the re-sampling programme confirms gold and silver mineralisation below and adjacent to the Calandria Sur rhyolite dome resource of 441,000 ounces gold equivalent (Indicated and Inferred). Encouragingly, LeachWell assays indicated high gold recoveries compared to dome-hosted primary mineralisation. Re-sampling results will be evaluated in conjunction with the forthcoming results of the recent drilling with the potential for a revised resource statement early 2013, if results are positive."

For tables of assay results and LeachWell test results click on the following link:

http://www.marianaresources.com/pdf/release/Mariana_120807a.pdf

For the figures referred to in this report click on the following link:

http://www.marianaresources.com/pdf/release/Mariana_120807b.pdf

Re-sampling Programme

The re-appraisal of volcaniclastic drill core was prompted by positive results from the last drill campaigns which discovered disseminated and veinlet/stockwork style gold mineralisation hosted by volcaniclastic rocks outside the rhyolite-hosted resource areas. To date, volcaniclastics on the dome flanks and beneath the dome have been re-sampled in a total of 48 drill holes. The first batch (Q1 2012) involved 638 samples from 22 holes and the second batch (Q2 2012) 809 samples from another 26 holes. Location of re-sampled drill holes is shown in Figures 2 (Second Batch) and 3 (First batch). Results for the two batches of re-sampling are summarised in Tables 1 and 2. The results of the first 15 holes from the first batch were released 3/4/12.

Eastern Border Volcaniclastics

The latest results include further significant gold assays in volcaniclastics east of the dome, in holes previously considered low priority:

--  11.0m @ 0.5 g/t Au 5 g/t Ag from 80.5m - CSD28
--  24.5m @ 0.8 g/t Au 12 g/t Ag from 83.5m - CSD103
--  7m @ 0.8 g/t Au from 18m - CSD262
--  7m @ 0.8 g/t Au from 6m - CSD278

In the previous release (3/4/2012), intersections included

--  52m @ 0.5 g/t Au from 8m - CSD11,
--  7m @ 0.9 g/t Au from 17m - CSD266
--  8m @ 1.0 g/t Au from 15m & 26m @ 0.6 g/t Au from 29m - CSD275 (See
    Figure 5).

Dome Base Volcaniclastics

The highlight was an intersection of27m @ 1.0 g/t Au, 13 g/t Ag in CSD105.

Further re-sampling of a broad zone of volcaniclastic-hosted veinlet/stockwork mineralisation associated with manganese carbonates intersected below the dome in CSD222, returned 1m @ 2.7 g/t Au 114 g/t Ag from 217m. This, together with previously released intersections of 3m @ 2.4 g/t Au & 12 g/t Ag from 147m and 6m @ 1.7 g/t Au & 17 g/t Ag from 207m, indicates mineralisation well below the dome base. Other re-sampling below the dome base has extended original intersections in several holes (For example, see Section G, Figure 4):

--  23m @ 0.5 g/t Au 5g/t Ag from 92m - CSD33
--  14m @ 0.5 g/t Au 6 g/t Ag from 73m - CSD91
--  27m @ 1.0 g/t Au 13 g/t Ag from 89m - CSD105
--  9.5m @ 1.2 g/t Au 19 g/t Ag from 113m - CSD106
--  13m @ 0.7g/t Au 5 g/t Ag from 85m - CSD107
--  7m @ 0.5 g/t Au from 111m - CSD107
--  15m @ 0.7 g/t Au from 65m - CSD111

Volcaniclastics LeachWell Assays

LeachWell assays were carried out on selected assay pulps of previously released intersections of volcaniclastic-hosted mineralisation (mostly primary sulphides, Figure 3) to indicate the percentage of gold recoverable by cyanidation for this style of mineralisation. The intersections are grouped into Eastern Border, Western Border and Below Dome Base (Table 3). High average recoveries are indicated, in comparison to the dome-hosted style primary mineralisation:

--  Eastern Border - 80% recovery (primary), 81% recovery (all samples) - 9
    holes
--  Western Border - 89% recovery (primary), 90% (all samples) - 3 holes
--  Below Dome Base - 63% (primary), 63% (all samples) - 24 holes

For comparison, average LeachWell gold extractions for Calandria Sur dome-hosted mineralisation averaged 95% oxide, 75% transition and 40% primary.

Phase V Drilling

Final results for the recently completed 21 hole (2,164m) diamond drill programme are expected in August. The holes were mostly designed to test new targets adjacent to and outside the current Calandria Sur resource limits and also to validate geological models following compilation of detailed exploration data. The programme included the deepening of six previous holes. The new drill results will be integrated with previous drilling and the re-sampling results.

Las Calandrias Project Background

Las Calandrias comprises multiple zones of gold and silver mineralisation hosted by rhyolite domes and volcaniclastics over a 12 sq km area. To date, 44,049m of drilling have been completed: Phase I (September-October 2009 - 1,566m), Phase II (March-April 2010 - 4,400m), Phase III (September 2010 - April 2011 - 29,738m), Phase IV (August-September 2011 - 6,181m) and Phase V (2,164m). The Phase V drilling comprised targets outside the Calandria Sur initial resource (19 holes) and Nido Este (2 holes).

Mariana released an initial NI 43-101-compliant resource of the Calandria Sur and La Calandria prospects of 491,000 ounces ('oz') AuEq Indicated and 28,000 oz AuEq Inferred on July 2011. The combined estimate was 11,840,000t @ 1.0 g/t gold (Au) and 17 g/t silver (Ag) Indicated and 870,000t @ 0.93 g/t Au and 5 g/t Ag Inferred.

Exploration Information

Exploration information in this announcement has been compiled by John Horsburgh who is a Fellow of the Australasian Institute of Mining and Metallurgy. Mr Horsburgh has sufficient experience relevant to the style of mineralisation and types of gold deposit under consideration and to the activity that he is undertaking to qualify as a Competent Person as defined in the JORC Code. Mr. Horsburgh is a qualified person within the meaning of National Instrument 43-101, Canada.

Quality Assurance/Quality Control

All technical information for the Company's Argentina projects is obtained and reported under a quality assurance and quality control (QA/QC) program. All samples are collected under the supervision of the Company geologists and dispatched via commercial transport to ALS Chemex laboratories in Mendoza, Argentina, and assayed in Chile. ALS Chemex's quality system complies with the requirements for the International Standards ISO 9001:2000 and ISO 17025: 1999. Samples returning greater than 10 g/t gold and/or greater than 100 g/t silver are assayed using gravimetric analyses. Systematic assaying of sample duplicates and commercially prepared standards and blanks is performed for analytical reliability.

LeachWell tests to determine the amount of cyanide extractable gold were completed by ALS Minerals in Mendoza, Argentina using their certified Au-AA15 method. The tests were completed on the assay pulps representing individual sample intervals or sample intervals combined by equal weights. After completion of each test only the gold in solution was assayed, and the percentage of gold extracted was calculated using the assayed head grade of the sample.

For further information please visit website at www.marianaresources.com.

About Mariana Resources

Mariana Resources Ltd is an AIM and TSX quoted exploration and development company with an extensive portfolio of gold, silver and copper projects in Argentina and Chile. In southern Argentina, the Company's core gold-silver projects are Las Calandrias (100%), Sierra Blanca (100%), Los Amigos JV (49%) and Aguila-Picadero (100%). These projects are part of a 200,000+ Ha land package in the Deseado Massif epithermal gold-silver district in mining-friendly Santa Cruz Province. In Chile, Mariana has a joint venture with US based international mining and natural resources company Cliffs Natural Resources Inc., to explore for iron oxide-copper-gold deposits in a 92,000 km2 area in north-central Chile along the highly prospective Atacama Fault Zone. Mariana is also evaluating a number of gold-silver and copper-gold opportunities away from the Cliffs JV area.

On 19 December 2011, Mariana announced that AngloGold had completed a strategic placement whereby AngloGold was issued 45,000,000 shares in Mariana at a price of 12 pence per share. AngloGold has the right to maintain its equity of 19.9% in Mariana in further issues by Mariana.

Safe Harbour

This press release contains "forward-looking information" within the meaning of Canadian securities legislation ("forward-looking statements"). These forward-looking statements are made as at the date of this press release and include, without limitation, statements regarding discussions of future plans, the realization, cost, timing and extent of mineral resource estimates, estimated future exploration expenditures, costs and timing of the development of new deposits, success of exploration activities, permitting time lines, and requirements for additional capital. The words "plans", "expects", "budget", "scheduled", "estimate", "forecasts", "intend", "anticipate", "believe", "may", "will", or similar expressions or variations of such words are intended to identify forward-looking statements. Forward-looking statements are subject to known and unknown risks, uncertainties, assumptions and other factors that may cause actual results to vary materially from those expressed or implied by such forward-looking statements, including, but not limited to: the effects of general economic conditions; the price of gold and silver; misjudgments in the course of preparing forward-looking statements; risks associated with international operations; the need for additional financing; risks inherent in exploration results; conclusions of economic evaluations; changes in project parameters; currency and commodity price fluctuations; title matters; environmental liability claims; unanticipated operational risks; accidents, labour disputes and other risks of the mining industry; delays in obtaining governmental approvals or in the completion of development or construction activities; political risk; and other risks and uncertainties described in the Company's annual information form and MD&A for the most recently completed financial year available on SEDAR. Although we believe that the expectations reflected in such forward-looking statements are based upon reasonable assumptions and have attempted to identify important factors that could cause actual results to differ materially from those contained in forward-looking statements, there may be other factors that cause results not to be as anticipated, estimated or intended. There can be no assurance that such statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such forward-looking statements. Accordingly, readers are cautioned not to place undue reliance on forward-looking statements. We do not undertake to update any forward-looking statements, except in accordance with applicable securities laws.

Incorporated in Guernsey registered number 44276.

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Contacts:

In Australia:

Mariana Resources Ltd

John Horsburgh

Chairman

+61 2 94374588


Mariana Resources Ltd

Glen Parsons

CFO

+612 94374588


RFC Ambrian Limited (Nomad)

Rob Adamson

+61 2 9250 0041


RFC Ambrian Limited (Nomad)

Will Souter

+61 2 9250 0050


In U.K.

Fox Davies Capital (Co UK Broker)

Jonathan Evans

+44 20 3463 5000


St Brides Media and Finance Ltd (PR)

Felicity Edwards

+44 20 7236 1177


RFC Ambrian Limited (Co UK Broker)

Klara Kaczmarek

+44 20 7634 4725


In Canada:

Mariana Resources Ltd (Vancouver Office)

Kathryn Witter

+1 604 669 9336
www.marianaresources.com