TORONTO, ONTARIO--(Marketwire - Sept. 18, 2012) - Nautilus Minerals (News - Market indicators)(OTCQX:NUSMF)(AIM:NUS) announces that its 100% owned subsidiary, Tonga Offshore Mining Limited ("TOML") confirmed that Golder Associates Pty Ltd., ("Golder") has completed a maiden Mineral Resource estimate for TOML's Clarion-Clipperton Fracture Zone ("CCZ") polymetallic nodule project, located within the Central Pacific Ocean (see Figure 1 in Links section).

The Inferred Mineral Resource has been reported at a range of abundance cut-offs, and is summarised in Table 1.

Table 1: Inferred Mineral Resource Estimate for TOML Areas A-D within the CCZ

Nautilus President and CEO Steve Rogers commented, "Our maiden mineral resource estimate for the CCZ again highlights the enormous potential of seafloor resources. We believe that the advance in processing and offshore technologies over the last 20 years now makes the extraction of these significant resources technically feasible."

The reduced social disturbance associated with deep sea mineral production and the development of a strong regulatory framework by the International Seabed Authority since 1994 are key elements that set this project apart from large land based resource developments.

Steve Rogers added that, "At Nautilus Minerals we are hugely excited to be leading the development of this enormous, currently untapped potential on the seafloor. Our priority focus must remain with our high grade Solwara 1 seafloor massive sulphide ("SMS") project, and other prospective SMS systems in PNG and Tonga. With the immense polymetallic nodule mineral resources of the CCZ however, we have to start the engineering and evaluation processes now to realise this opportunity at the appropriate time in the future. There is the potential for a further update of this mineral resource estimate, in that approximately 30% of our licence area is not included in the estimate (Areas 2E and 2F in Figure 1), but both of these areas are known to have nodules present from limited sampling work carried out to date." 

Links

Figure 1 - www.nautilusminerals.com/s/PhotoGallery-Maps.asp

General Background:

The nodules occur within the CCZ of the tropical north Pacific, in water depths generally between 4,000 and 6,000 meters. They contain significant grades of manganese, nickel, copper and cobalt, and form by the precipitation of metals on the seafloor, either directly from ocean waters or via decomposing microorganisms and/or their effluent in benthic sediments.

Basis of the Mineral Resource Estimate:

Golder has estimated the Mineral Resource for the TOML CCZ project using:

• Sample data collected by "pioneer contractors"  (Deep Ocean Resources Development Company (DORD, of Japan), Association Francaise d'Etude et de recherché des NODules oceaniques (AFERNOD, of France), Yuzhmorgeologiya (state owned company of the Russian Federation)), and provided to TOML and Golder by the International Seabed Authority;
• Ordinary Kriging for nickel, cobalt, copper and manganese grades; and
• Inverse Distance for nodule abundance and tonnage.

Samples used for the resource were collected by the pioneer contractors during various exploration cruises, using free-fall-sampling devices. The resulting samples were stored on the vessel, and then on arrival at port dried and crushed. Nickel, copper, iron and cobalt were normally assayed using atomic absorption, with manganese measured by photometric (electrometric) titration. The resulting sample locations and assay results were presented to the International Seabed Authority ("ISA") as part of the process whereby the pioneer contractors hand over half of their prospect areas (of equal value) to the ISA for inclusion in the "Reserve Area" set aside for developing nations such as Tonga.

The data provided by the contractors is not supplied with any quality assurance or quality control ("QAQC"), although some QAQC is known to have been performed at the time (there was no requirement however, to submit this to the ISA). TOML has accessed this data for the purpose of this Mineral Resource estimate. As part of the verification requirements Golder also contacted pioneer contractors directly to provide confirmation of the data sets and methodologies used. Checks were also undertaken; by comparison of the different data sets (those covering the TOML blocks) and by comparison of this data with the larger ISA dataset covering the entire CCZ (see Tables 2 to 8 below for raw sample statistics). These checks showed that:

• Only four of the total 2,212 data points provided were suspected of being erroneous (and are likely data entry errors that occurred with the one contractor);
• Box plots and log-probability plots comparing the various assay data and distributions show the TOML abundance, Ni, Cu, Co, and Mn data compare well with the full ISA data set. Variations between the data sets are attributed to both spatial variability and minor differences in sampling and assaying methods of the various contractors; and
• Quantile-Quantile (QQ) plots show the TOML abundance, Ni, Cu, Co and Mn data compare well with the total ISA data base, but with divergence at the tails of the distributions, while Co and nodule abundance tend to be biased slightly lower for the TOML data.

Assay data for the four key elements (Ni, Cu, Co, and Mn) are very consistent and widespread over large areas of the CCZ. The key variable for future resource classification is nodule abundance. Determining short range variability for nodules will be required to increase resource classification to higher levels of indicated and measured.

The verification also involved review of the data by the independent Qualified Person Dr. Charles Morgan. Dr. Morgan has considerable experience in the CCZ nodules, having been a scientist on board the Lockheed Martin consortia program in the 1980s, and having been a consultant to the ISA in various capacities including as a member of the Legal and Technical Commission, and in the preparation of resource estimates for the ISA. Golder considers the sampling data is suitably supported and maintained by the ISA for use in the calculation of an inferred resource.

The estimate is current as of September 18, 2012, and only incorporates blocks A to D of the TOML licence (approximately 70% of the licence area). Blocks E and F are known to host nodules from limited sampling, and represent significant exploration upside to the Mineral Resource (see tables 6 and 7 below). Additional elements are reported to be present in CCZ nodules, with Rare Earth Elements being of particular note, and these provide additional potential for the project. All of the blocks are located at a depth of between 4,000 metres and 6,000 metres below sea level.

Other Relevant Information:

The ISA is an autonomous international organisation established under the United Nations Convention on the Law of the Sea ("UNCLOS") and the 1994 Implementation Agreement. The ISA regulates the "area" beyond national jurisdiction (the "AREA"), under the terms of UNCLOS and the Law of the Sea. As of 15 May 2011, UNCLOS has been signed by 162 parties, mostly independent states and the European Union. The only notable absentee signatory is the United States of America. Part XI of UNCLOS and its subsequent implementation Agreement of 1994, deals with mining of minerals from the seafloor in the AREA.

The ISA has also developed regulations for prospecting and exploration for polymetallic nodules, seafloor massive sulphides, and cobalt rich crusts within the AREA. On 11 January 2012, TOML signed a Contract for Exploration for Polymetallic Nodules with the ISA covering an area of approximately 75,000 km², in six blocks within the CCZ. TOML is registered in the Kingdom of Tonga, is subject to the laws of Tonga, and is sponsored by the Kingdom of Tonga under the Law of the Sea. The Contract is for an initial term of 15 years.

The ISA, at its 18^th session in Jamaica in 2012, started the process of developing regulations to cover the exploitation of nodules. Royalties and taxes payable on any future production from the property will only be finalised once the ISA has developed its exploitation code. The code will need to include the key principles of UNCLOS.

TOML has agreed to a royalty with the Tongan government as part of its sponsorship agreement of US$1.25 per dry ton for the first 3 million dry tons of nodules mined per year, and US$0.75 per dry ton for all subsequent tons mined thereafter in that same year. Nautilus and TOML are parties to a contract with Nauru Ocean Resources Inc. ("NORI") and NORI's current shareholders, pursuant to which Nautilus increased its indirect ownership interest in TOML from 50% to 100% in exchange for its 50% indirect interest in NORI. That contract provides, among other things, a value normalisation process in respect of TOML and NORI's licences to explore polymetallic nodules in the AREA. The process is triggered by TOML and NORI achieving a resource pursuant to NI-43-101. NORI has not yet disclosed a resource estimate in respect of its licences.

Recommendations:

It is recommended that future work on the TOML licences aim to determine an Inferred Mineral Resource estimate for Areas E and F and increase the resource classification for parts of the other areas to Indicated or Measured Mineral Resource. Additionally, key modifying factors will be constrained to a point where a Mineral Reserve may potentially be estimated. It is recommended that future work include:

Exploration Phase

• Exploration surveys for detailed bathymetry.
• Sampling on TOML Areas E and F to define Inferred Mineral Resources for these areas.
• Sampling at sufficient detail on the best of the defined Inferred Mineral Resources to define short range variability, assay variance and trends, density, and other critical data.
• Assaying of all samples collected for additional elements, including but not limited to REE, potential "contaminants", and any other elements that may aid economic studies.
• Widespread and detailed study of dry and wet density of the nodules on the TOML licence including study of free and crystallisation water contents.
• Side scan sonar survey of TOML licence areas where appropriate to image nodule occurrence.
• Baseline environmental studies.

Study Phase

• Engineering and metallurgical studies and design work for both the onshore and offshore components.
• Preliminary economic and commercial studies to provide scoping estimates for CAPEX and OPEX for mining, transportation and processing options.

Possible budgets required to complete the exploration phase over the next two years may total $US2 million to $US4 million. Nautilus has sufficient funds to undertake this work or may choose to look for a partner.

Mr Mathew Nimmo of Golder as independent Qualified Person has prepared the technical information that forms the basis for this press release.

Pursuant to NI 43-101, Nautilus Minerals will file an independent technical report within 45 days in respect of this mineral resource estimate.

(i)based on a 6kg/m2 abundance cut off

Certain of the statements made in this news release may contain forward-looking statements within the meaning of the United States Securities Exchange Act of 1934 and forward-looking information within the meaning of applicable Canadian securities law. Forward-looking statements and forward-looking information include, but are not limited to statements or information with respect to the potential commercial extraction of seafloor resources in the CCZ, further development of TOML's CCZ territory and other potential resources in TOML's CCZ territory. We have made numerous assumptions about the material forward-looking statements and information contained herein. Please refer to the company's most recently filed Annual Information Form in respect of material assumptions and risks relevant to forward looking information. With respect to the CCZ, the "Exploration, Development and Operating Risks" section of the AIF should be read with the particular attributes of the CCZ, versus the Company's Bismarck Sea prospects, in mind. These include the fact that the ocean floor in the CCZ is at much greater depth, the fact that the CCZ is in the middle of the Pacific Ocean and the fact that the Company's plans for developing the CCZ are at a much earlier stage than its plans in respect of its Solwara projects. Even though our management believes the assumptions made and the expectations represented by such statements or information are reasonable, there can be no assurance that the forward-looking statement or information will prove to be accurate.
Forward-looking statements and information by their nature involve known and unknown risks, uncertainties and other factors which may cause the actual results to be materially different from any future results expressed or implied by such forward-looking statements or information. Such risks, uncertainties and other factors include, among others as described in the most recently filed Annual Information Form, the risk that the amount of metals contained in the company's deposits may differ from estimates of resources, the risk that any permits required for development of the CCZ will not be available to the Company, risks associated with financing and executing the required work programs and associated studies, other risks associated with metallurgical properties of the resource, environmental studies, people retention, technology development, intellectual property, logistical support in the CCZ, political interference (from both within and outside the ISA), excessive and/or unwarranted non-government organisation attention and/or misinformation campaigns, risks associated with maintaining the companies TOML sponsorship. Should one or more of these risks, uncertainties or other factors materialize, or should underlying assumptions prove incorrect, actual results may vary materially from those described in forward-looking statements and information. Although we have attempted to identify factors that would cause actual results to differ materially from those described in forward-looking statements and information, there may be other factors that cause actual results, performances, achievements or events to not be as anticipated, estimated or intended. Also, many of the factors are beyond our control. There can be no assurance that forward-looking statements or information will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Accordingly you should not place undue reliance on forward-looking statements or information. Except as required by law, we do not expect to update forward-looking statements and information as conditions change and you are referred to the full discussion of the Company's business contained in the Company's reports filed with the securities regulatory authorities in Canada.

For more information please refer to www.nautilusminerals.com.

About Nautilus Minerals Inc.

Nautilus is the first company to explore the ocean floor for polymetallic seafloor massive sulphide deposits and is developing its first project at Solwara 1, in the territorial waters of Papua New Guinea, where it is aiming to produce copper, gold and silver. The company has been granted all necessary environmental and mining permits.

Nautilus also holds more than 500,000 km² of highly prospective exploration acreage in the western Pacific; in PNG, the Solomon Islands, Fiji, Vanuatu and Tonga, as well as in international waters in the eastern Pacific.

A Canadian registered company, Nautilus is listed on the (News - Market indicators) and (AIM:NUS) stock exchanges and (OTCQX:NUSMF). Its corporate office is in Brisbane, Australia. Its major shareholders include Metalloinvest, the largest iron ore producer in Europe and the CIS, which has a 21% holding, global mining group Anglo American, which holds an 11.1% interest and MB Holdings, an Oman based group with interests in mining, oil & gas, which holds a 16.9% interest.