Duluth Metals Signs Definitive Participation Agreement with Antofagasta plc on Nokomis Project

TORONTO, July 21, 2010 - Duluth Metals Limited ("Duluth") (TSX: DM)
(TSX:DM.U) is pleased to announce that it has signed the formal definitive
participation agreement ("PA") with Antofagasta plc ("Antofagasta") (LSE:
ANTO.GB), which implements the previously announced Heads of Agreement (see
SEDAR filing and press release dated January 14, 2010) on the joint venture
development of the Nokomis Project in northeast Minnesota, USA. The signing
of the PA allows the ramp-up of activities, which will see US $130 million
spent over the next three year period to advance the project towards a
bankable feasibility study, subject to all applicable government and
regulatory approvals.

The joint venture brings in a major global mining partner with financial
capability and proven expertise in building and operating large mining
projects to aggressively accelerate the development of this large scale
copper-nickel-platinum-palladium-gold project. The new joint venture
company, Twin Metals Minnesota LLC ("Twin Metals"), is 60% owned by Duluth
and 40% by Antofagasta. A new management team is currently being formed.
Both Antofagasta and Duluth are appointing three representatives to the
Board of Directors of Twin Metals.

Under the terms of the PA, Antofagasta will provide US $130 million in
direct funding to the project as its initial contribution to the joint
venture. Upon making such contribution and completing a bankable feasibility
study, Antofagasta has the option to acquire an additional 25% equity
interest in Twin Metals based on an exercise price calculated in a pro-rata
share of 1.0 times Net Present Value of the project, which will be
determined by the bankable feasibility study. Under the terms of the PA,
Antofagasta has agreed to provide Duluth additional loan and financing
facilities of up to US$30 million to cover Duluth's share of subsequent
project expenditures, which will ultimately be repayable in cash, Duluth
shares or offset against the 25% option exercise price. Full draw down by
Duluth of the additional loan and financing facilities totaling US$30
million, together with the commensurate Antofagasta spending contribution,
would make available an additional US$85 million of potential funding to
the project for expenditures beyond the $130 million commitment by
Antofagasta. In addition, Antofagasta has undertaken to organize a common
project financing for the large capital cost financing requirements of the
project. Duluth expects development activities at Nokomis to proceed on an
accelerated basis and anticipates pre-feasibility and bankable feasibility
studies to be the focus of activities over the next 24-36 months.

As part of the PA, Duluth Metals is retaining approximately 31,000 acres
of mineral interests on exploration properties adjacent to and near-by the
joint venture holdings. In addition to actively participating in the joint
venture on Nokomis, Duluth Metals will undertake a large scale exploration
program on its retained exploration properties.

Currently, the Nokomis deposit is estimated to contain 550 million
tonnes of Indicated Resources grading 0.639% copper, 0.200% nickel and
0.660 grams per tonne TPM (platinum-palladium-gold) for a copper equivalent
(CuEq) grade of 1.51%, plus an additional 274 million tonnes of Inferred
Resources grading 0.632% copper, 0.207% nickel and 0.685 grams per tonne
TPM for a CuEq grade of 1.53% (See Dec 9, 2009 NI 43-101 "Technical Report
on the Mineral Resource Estimate for the Nokomis Deposit" and press release
dated Dec. 11, 2009 available at www.Duluthmetals.com).

Minnesota is a mining friendly state which has more than a century of
mining history. The mining district in northeastern Minnesota has excellent
mining infrastructure, including power, well-developed roads, railway
networks, equipment-supply centers, a highly productive local labor force
and proximity to three deep water ports on the north shore of Lake Superior.

David Oliver, P. Geo. is the Qualified Person and Project Manager for
Duluth, in accordance with NI 43-101 of the Canadian Securities
Administrators, and is responsible for the technical content of this press
release and quality assurance of the exploration data and analytical
results.

On the Antofagasta transaction, Duluth's financial advisor is UBS
Securities Canada Inc. and Canadian legal advisor is Fraser Milner Casgrain
LLP.

About Duluth Metals

Duluth is committed to acquiring, exploring and developing copper,
nickel and platinum group metal (PGM) deposits. Duluth's principal property
is the Nokomis Property located within the rapidly emerging Duluth Complex
mining camp in northeast Minnesota. The Duluth Complex hosts one of the
world's largest undeveloped repositories of copper, nickel and PGMs,
including the world's third largest accumulation of nickel sulphides, and
one of the world's largest accumulations of polymetallic copper and
platinum group metals.

About Antofagasta plc

Antofagasta has three business divisions: Mining, Transport and Water.
Antofagasta Minerals S.A., the mining division, is one of the world's
largest copper producers. Its activities are mainly concentrated in Chile
where it owns and operates three copper mines with a total production of
442,500 thousand tonnes of copper and 7,800 tonnes of molybdenum in 2009.
Antofagasta has recently commissioned a brownfield expansion at its Los
Pelambres mine and a new mine development, Esperanza, is expected to enter
into production at the end of 2010. Together, these are expected to increase
group copper production by approximately 60% to over 700,000 tonnes from
2011. A feasibility study is also in progress at Antucoya in Northern Chile.
In Pakistan, a feasibility study is at its final stages at the Reko Diq
joint venture. Antofagasta also has exploration programs in Africa, Europe
and the Americas.

"This document may contain forward-looking statements (including
"forward-looking information" within the meaning of applicable Canadian
securities legislation and "forward-looking statements" within the meaning
of the US Private Securities Litigation Reform Act of 1995) relating to,
among other things, Duluth's operations, the environment in which it
operates, timing and amount of capital expenditures, results of exploration
and mine development, the availability of funding to Duluth and timing of
geological reports. Such statements are based on operations, estimates,
forecasts and projections. They are not guarantees of future performance
and involve known and unknown risks, uncertainties and other factors that
are difficult to predict and may be beyond Duluth's control. A number of
important factors could cause actual outcomes and results to differ
materially from those expressed in forward-looking statements, including
those set forth in Duluth's annual information form under the heading
"Risk Factors" and in Duluth's other public filings. Consequently, undue
reliance should not be placed on such forward-looking statements. In
addition, all forward-looking statements in this press release are given as
of the date hereof. Duluth disclaims any intention or obligation to update
or revise any forward-looking statements, whether as a result of new
information, future events or otherwise, save and except as may be
required by applicable securities laws.

For further information: Mara Strazdins, Director of Corporate
Communications, +1(416)369-1500, mstrazdins@Duluthmetals.com; Dr. Henry J.
Sandri, President and CEO, +1(651)389-9990, hsandri@Duluthmetals.com; Web
Page: www.Duluthmetals.com

For further information: Mara Strazdins, Director of Corporate Communications, +1(416)369-1500, mstrazdins at Duluthmetals.com; Dr. Henry J. Sandri, President and CEO, +1(651)389-9990, hsandri at Duluthmetals.com