Nautilus Confirms High Grades in Phase One of 2009 Tongan Exploration

Nautilus Minerals Inc. has received high-grade copper, gold, zinc and silver assays with highest assay results in respect of each element across all the samples tested of 12.6 per cent Cu, 34.0 grams per tonne Au, 60.9 per cent Zn and 185 g/t Ag. The assay results relate to the samples taken during the first phase of its 2009 target generation program in Tonga, on 100-per-cent-owned Nautilus prospecting licences. The second phase of the Tongan program is currently under way.

Stephen Rogers, chief executive officer of Nautilus, commented: “We are excited about the high grades of these assay results. In particular, the very high gold and silver grades are impressive. The delineation of more ‘precious metal’ rich, high-grade seafloor massive sulphide (SMS) systems further highlights the prospectivity of our large tenement package in Tonga. We have commenced the second phase of our 2009 Tongan exploration program and will remain on the water until the end of June. We look forward to receiving the results of this program.”

Twenty samples of SMS material were collected from Tahi Moana 7 and FRSC02 prospects, reported previously, during phase one of the 2009 Tongan exploration program. Assay results confirm the two systems contain significant precious metals (gold and silver), as well as high-grade copper and/or zinc mineralization.

Phase two of the 2009 Tongan exploration program commenced on Saturday, May 30, 2009. It consists of approximately 27 days of water column sampling, bathymetric surveying and rock sampling. The program, like phase one, is being undertaken in collaboration with Australian National University (ANU), and the Commonwealth Scientific and Industrial Research Organisation (CSIRO), on board the Marine National Facility research vessel Southern Surveyor. Work is being completed under the supervision of ANU’s Prof. Richard Arculus, with input from CSIRO and Nautilus. Phase one of the program delineated 12 anomalies, and was reported previously.

Qualified person

The exploration results reported in this announcement have been compiled under the supervision of Michael Johnston, vice-president strategic development of Nautilus Minerals. Mr. Johnston is a member of the Australasian Institute of Mining and Metallurgy, has over 25 years experience in mining and exploration geology, and is a qualified person as defined by National Instrument 43-101. He consents to his name being used in this release.

Laboratory analyses

Laboratory analyses were completed by ALS Laboratory Group in Brisbane, Australia. ALS operates quality systems based on international standards ISO/IEC17025:1999 “General requirements for competence of calibration and testing laboratories” and ISO9001:2000 “Quality Management Systems — Requirements.”

Gold was determined using a 30-gram fire assay with aqua regia digest (ALS technique Au-AA25). Copper, lead, zinc and silver were determined by aqua regia digest followed by an inductively coupled plasma atomic emission spectroscopy (ICP-AES) finish (ALS technique ME-OG46). Very high-grade zinc (greater than 30 per cent) was reassayed by method ME-OG46, but using a more diluted digest (ALS technique ME-ICPDil). Iron was determined using a four-acid digest with ICP-AES finish (ALS technique ME-ICP61).

Sampling methodology

Samples were collected during the deployment of a small dredge, with the exception of sample FRSC02 which was collected from the frame of the camera tow. A small reference sample was retained for each sample (except FRSC02), with the bulk of the sample dispatched to ALS for sample preparation and assaying. All sampling was completed under the supervision of Nautilus personnel.

Quality assurance

Standards were submitted with the samples, and results assessed to be within acceptable tolerances.