Altamira Gold Reports over 90% Gold Recoveries from Initial Metallurgical Tests on Drill Samples from the Maria Bonita Target, Cajueiro Project, Brazil

March 02, 2023 8:30 AM EST | Source: Altamira Gold Corp.

Vancouver, British Columbia--(Newsfile Corp. - March 2, 2023) - Altamira Gold Corp. (TSXV: ALTA) (FSE: T6UP) (OTC Pink: EQTRF), ("Altamira" or the "Company") is pleased to announce that it has received the results of initial metallurgical characterisation tests on two composite drill core samples from the recently completed scout diamond drill campaign at the Maria Bonita target within the Cajueiro project in Para state, Brazil.


  • Cyanide leach in a 24-hour agitated leach test at a grind size of 80% passing the 75µm screen recovered 92% of total gold content in a saprolite composite (oxide) sample, while the fresh rock composite sample recovered 90% of gold content.
  • Drill assay composite head grades for the saprolite (1.2g/t gold) and fresh rock (1.1g/t gold) correspond well with the laboratory head grades of 1.3g/t and 1.07g/t gold respectively.
  • Average cyanide (0.11kg/t) consumptions were very low by industry standards (0.45-0.75kg/t) as a result of very low sulphide contents in the mineralized material.

Consulting metallurgist Ian Gordon Hall Dun BSc (Eng), MSc. (who has 45 years of experience as a metallurgist in Brazil) observed, "The main body of tests were conducted at a specialist laboratory in Brazil (Testwork Desenvolvimento de Processo Ltda) which is highly regarded for its evaluation of gold ores. Initial results show excellent gold recoveries from both the saprolite and hard rock samples in an agitated cyanide leach test. These initial results point successfully in the direction of a heap leach scenario with high Au recovery and modest reagent consumptions. More laboratory testing will now be focused on that heap leach scenario."

Altamira Gold President and CEO, Michael Bennett, commented, "The excellent assay results from the initial drillholes at Maria Bonita were sufficiently encouraging for us to immediately commission metallurgical tests on the mineralized material. We are very pleased with these initial test results as they show the potential for high gold recoveries in the 90% range for both saprolite and fresh rock. Importantly, key leach reagent consumptions were low and the tests confirmed that the mineralization does not contain significant deleterious elements. With these positive metallurgical results in hand, we will continue the planning of a follow up drill campaign aimed at determining the size of the mineralized body."


The Cajueiro project is located approximately 75km NW of the town of Alta Floresta in the state of Mato Grosso (Figure 1) in central western Brazil and is easily accessible by road and has grid power. Cajueiro forms one of three key projects that Altamira controls in the region, the other two being Apiacas and Santa Helena (Figure 1).

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Figure 1: Location of the Cajueiro, Apiacas and Santa Helena projects.

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The Cajueiro project has current NI 43-101 resources of 5.66Mt @ 1.02 g/t gold for a total of 185,000 oz in the Indicated Resource category and 12.66Mt @ 1.26 g/t gold for a total of 515,000 oz in the Inferred Resource category.

Several strong mainly untested gold-in-soil anomalies occur within a short radius of the Cajueiro resource area and include Maria Bonita, Sossego and Novo Sonho (Figure 2). Maria Bonita is the strongest of these peripheral gold-in-soil anomalies and is open to the west, with the current footprint of the geochemical anomaly covering an area comparable in size to the entire Cajueiro mineral resource area.

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Figure 2: Location of the Cajueiro (Baldo) mineral resource and the Maria Bonita target showing relative size and intensity of the soil responses. The Maria Bonita soil anomaly remains open to the west and north.

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Maria Bonita Target

The Maria Bonita target is located approximately 7km northwest of the Cajueiro resource area (Figure 2) and is defined by a gold-in-soil anomaly which is at least 800 x 800m in size and open to the west. The central part of the anomaly returned gold values in excess of 1g/t gold in soils (Figure 3).

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Figure 3: Gold-in-soil values at the Maria Bonita target over background aero-magnetic data (derivative of total magnetic intensity - TMI) with structural interpretation.

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Following completion of holes MBA001-MBA004 (see press releases dated September 7 and November 16, 2022), representative composite samples of saprolite and fresh rock were prepared from assay sample coarse rejects, returned from the analytical laboratory. Each sample weighed 20kg and was comprised of 15 subsamples of individual core intervals, each of which measured 0.77-1.5m.

The calculated head grades from prior assay results were 1.2g/t Au for the saprolite and 1.1g/t Au for the fresh rock samples.

The samples were submitted to Testwork Desenvolvimento de Processo Ltda in Nova Lima, Minas Gerais, Brasil. The testwork was conducted under the observation of the Company's consulting metallurgist Ian Gordon Hall Dun BSc (Eng), MSc. who specialises in gold and tin processing and has wide experience in Latin American projects, having resided in the region for 45 years.

 Au g/t >35# <35# Calc head Est head
 Saprolite 1.39 1.24 1.30 1.2
 Fresh Rock 0.91 1.15 1.07 1.1


Table 1: Estimated head grades (from drill assay composites) versus calculated head grades (from laboratory sizing analysis)

The laboratory calculated head grades for the samples were 1.30g/t Au and 1.07g/t Au respectively which correlate well with the estimated head grades from the individual drill core residue composites.

The testwork programme included leaching, gravity, magnetic and froth flotation characterisation tests. The samples were submitted in a crushed state, nominally passing 3mm. A screening of a 3kg sub-sample of the head material at 35# (500µm), showed that 43% (saprolite) and 72% (fresh rock) of the contained gold is in the <35# fraction.

The sample material was reduced to 80% passing 75µm for successive tests.

Direct agitated leaching tests were conducted on two sub-samples of each main sample (saprolite and fresh rock). The results showed 89.9 to 92.8% gold recoveries at low reagent consumption rates as outlined below.

Au recovery %Test 1Test 2
Fresh Rock 89.990.5


Table 2: Gold recovery from direct leach tests

Lime kg/tNa CN g/t
Test 1Test 2Test 1Test 2
Fresh Rock 0.80.758892


Table 3: Main reagent consumption for direct leach tests

Industry average cyanide (CN) consumption rates generally lie in the range 450-750g/t (grams per tonne of ore treated). Therefore, the initial tests are highly encouraging that a low cyanide consumption may be anticipated. Consumption of lime for pH modification in fresh rock is also well below an industry benchmark of ~2kg/t.

A combination of gravity and flotation tests produced average gold recoveries of 68% (fresh) and 69% (saprolite), which suggest that further work is warranted via those routes to optimise a metallurgical plan, underpinned by the 90% recoveries obtained from direct leaching.

As a next-step, the Company plans to conduct preliminary tests on crushing and grinding characteristics plus amenability of the leach dynamics to heap leaching.

Qualified Person

Guillermo Hughes, FAIG and M AusIMM., a consultant to the Company as well as a Qualified Person as defined by National Instrument 43-101, supervised the preparation of the technical information in this news release.

About Altamira Gold Corp.

The Company is focused on the exploration and development of gold projects within western central Brazil. The Company holds 8 projects comprising approximately 190,000 hectares, within the prolific Juruena gold belt which historically produced an estimated 7 to 10Moz of placer gold. The Company's advanced Cajueiro project has NI 43-101 resources of 5.66Mt @ 1.02 g/t gold for a total of 185,000 oz in the Indicated Resource category and 12.66Mt @ 1.26 g/t gold for a total of 515,000oz in the Inferred Resource category.

On Behalf of the Board of Directors,


"Michael Bennett"

Michael Bennett
President & CEO

Tel: 604.676.5660

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The securities described herein have not been registered under the U.S. Securities Act or any state securities laws, and may not be offered or sold in the United States absent registration or an applicable exemption from registration requirements under the U.S. Securities Act and any applicable state securities laws.

Forward-looking Statements

Certain information contained herein constitutes "forward-looking information" under Canadian securities legislation. Forward-looking information includes, but is not limited to, statements with respect to the extension of the Warrants. Generally, forward-looking information can be identified by the use of forward-looking terminology such as "will", "intends" or variations of such words and phrases or statements that certain actions, events or results "will" occur. Forward-looking statements are based on the opinions and estimates of management as of the date such statements are made and they are subject to known and unknown risks, uncertainties and other factors that may cause the actual results to be materially different from those expressed or implied by such forward-looking statements or forward-looking information, including the receipt of all necessary regulatory approvals. Although management of the Company has attempted to identify important factors that could cause actual results to differ materially from those contained in forward-looking statements or forward-looking information, 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 statements. Accordingly, readers should not place undue reliance on forward-looking statements and forward looking information. The Company will not update any forward-looking statements or forward-looking information that is incorporated by reference herein, except as required by applicable securities laws.


Gold analysis has been conducted by SGS method FAA505 (fire assay of 50g charge), with higher grade samples checked by FAA525. Analytical quality is monitored by certified references and blanks. Until dispatch, samples are stored under the supervision the Company's exploration office. The samples are couriered to the assay laboratory using a commercial contractor. Pulps are returned to the Company and archived. Drill holes results are quoted as down-hole length weighted intersections.

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