Stillwater Issues Letter and Mails Definitive Proxy Materials to Shareholders

Stillwater Mining Company (NYSE:SWC) (TSX:SWC.U) ('Stillwater? or the
'Company?) today announced that it has filed definitive proxy materials
with the Securities and Exchange Commission (SEC) in connection with the
Company′s 2013 Annual Shareholders Meeting, which will be held on May 2,
2013.

The Board of Directors of Stillwater has also issued a letter to its
shareholders urging them to vote for Stillwater′s highly-qualified slate
of director nominees who have positioned the Company for meaningful
platinum group metals (PGM)-focused growth at a time when PGM market
dynamics are increasingly robust.

All shareholders of record as of March 6, 2013 are entitled to vote at
the 2013 Annual Shareholders Meeting. Stillwater encourages all
shareholders to carefully review its definitive proxy filing and other
materials and vote only their WHITE proxy card. For more information
about Stillwater′s 2013 Annual Shareholders Meeting, please visit www.supportstillwater.com.

The full text of the letter follows:

March 20, 2013

Dear Fellow Shareholder:

YOUR VOTE IS IMPORTANT ?

PLEASE VOTE THE WHITE
PROXY CARD TODAY

Under the leadership of our current Board and through the execution of a
multi-year plan, Stillwater has positioned itself for meaningful
platinum group metals (PGM)-focused growth at a time when PGM market
dynamics are increasingly robust. Today, Stillwater is in a position to
deliver increased shareholder value as many of our industry peers face
significant operational and financial challenges. As such, we are
pleased to inform you that the Company has nominated all of Stillwater′s
qualified directors for reelection at the annual meeting.

Given the Company′s strong position and positive momentum, it is
disappointing that a hedge fund, the Clinton Group, is waging a battle
for control of your Company even though it only recently acquired just
1.2% of our outstanding shares and has no relevant experience investing
in mining companies. In fact, according to public filings, the Clinton
Group has only invested in 18 mining companies, none of them
PGM-focused, with an average holding period of only 1.2 quarters,
suggesting a significant short-term bias. At Stillwater, the Clinton
Group has leveled a number of misguided criticisms and self-serving
demands against the Company which either (a) offer no new strategies
that the Board is not already pursuing, or (b) are misinformed and/or
misdirected and will, in our view, be value-destructive for Stillwater′s
shareholders.

Your vote is critical and we need your support at our upcoming Annual
Meeting scheduled for May 2, 2013. Do not cede control of your
Company to a dissident hedge fund with a misguided, value-destructive
agenda. We urge you to vote your WHITE proxy card FOR your
Company′s nominees TODAY by telephone, Internet, or by signing, dating,
and returning the WHITE proxy card in the postage-paid envelope
provided with our recently mailed Annual Meeting materials.

YOUR BOARD HAS POSITIONED STILLWATER TO DELIVER

INCREASED
VALUE TO ALL SHAREHOLDERS

Stillwater is the premier North American PGM producer. The Company has
taken decisive actions over the past five years to become an industry
leading low-cost PGM producer, both in terms of current annual PGM
production, as well as PGM-focused growth initiatives going forward.
Stillwater is particularly well-positioned to deliver significant value
for shareholders in light of structurally embedded global supply
constraints and growing worldwide demand for PGMs ? especially palladium.

Palladium Market Fundamentals Are Stronger Than Ever

While palladium and platinum prices on average were substantially lower
in 2012 than in the prior year, PGM market fundamentals are robust and
sit at a positive inflection point, particularly with respect to
palladium. Palladium has solidified its position as the PGM-of-choice in
the auto market, and worldwide auto production is expected to grow by
25% over the next three years. At the same time, PGM mine supply remains
significantly constrained and the once-vast inventory backlog of Russian
palladium supply now appears to be depleted. Against this backdrop, we
expect PGM prices to increase from their current strong levels, and the
palladium price, in particular, to be an outperformer.

2012 Represented Another Strong Operational Year for Stillwater

2012 annual production and cash costs were better than guidance, and our
total ore reserves in Montana are at an all-time high. At the same time,
2012 was the Company′s safest year in its history and we maintain
excellent relations with our employees, unions and NGOs.

CLINTON GROUP OFFERS NO NEW IDEAS TO CREATE SHAREHOLDER VALUE

The Clinton Group has made several recommendations that ignore the fact
that Stillwater has already been pursuing a
strategy to extend mine life and enhance PGM production in its North
American assets. One could conclude that the fact that
Clinton is recommending actions that have already been implemented
implies a fundamental lack of understanding of our business. Over the
past several years, your Board has undertaken the following actions:

• We are accelerating our spending and development
  of our Montana growth projects. In many ways, 2012 was a key
  inflection point in terms of the comprehensive growth plan and
  strategy we implemented in 2010 in an effort to identify and pursue
  high-value PGM growth targets within our J-M Reef ore body in Montana.
  As a result of that effort begun in 2010, today we are pursuing three
  separate PGM projects? Graham Creek, Far West and Blitz ? that will
  broaden the reach of our Montana mines and increase our annual
  production by as much as 20% over the next several years. To that end,
  87% of our 2013 capex budget has been allocated to maximizing and
  increasing our Montana PGM production.
  
• We are working hard towards completing a final
  updated engineering study on Marathon as soon as possible. Our
  Marathon PGM-copper project in Canada remains the only advanced
  palladium-focused project of scale in North America. We are working
  hard towards a final updated engineering study in the third quarter of
  2013 and we continue to believe that the project is a highly
  attractive asset for our overall PGM portfolio. Our enthusiasm for
  this project is shared by our partner Mitsubishi Corporation, which
  invested $81 million in Marathon to acquire a 25% stake in March 2012.
  

Additionally, the Clinton Group has made a number of demands that
highlight their lack of experience in mining and, we believe, will
be destructive to the value of your investment.

• Abandoning Altar now would be imprudent and
  value destructive. Our world-class Altar copper-gold
  exploration project in Argentina is a natural hedge to any unexpected
  volatility in PGM pricing, and was acquired to provide important
  asset-class risk and commodity diversification. Given the ongoing
  price re-rating of palladium to platinum, coupled with our belief in
  the sustainability of strong market conditions supporting robust PGM
  pricing, we intend to emphasize investment in PGMs. Pursuing 'forced?
  monetization alternatives for Altar at this time, particularly given
  our ability to advance the project on a relatively limited budget to
  prove out its significant upside, will not serve to maximize
  shareholder value.
  
• Eliminating palladium marketing removes the only
  industry support for a re-rating against platinum. Every
  additional ounce of palladium demand we can potentially help
  facilitate, directly or indirectly, is of critical importance to our
  operational results. Outsized demand of palladium provides important
  support for a re-rating vs. platinum and general overall price
  strength. We have seen this occur over the past two years, where the
  palladium price has re-rated to 42% of platinum, on average, vs. 26%
  of platinum, on average, for the eight years prior. The impact of
  this re-rating is approximately $120 million of annual cash flow.
  We cannot afford to sit on the sidelines and not exert influence. The
  fact that we are the only one attempting to promote this re-rating,
  and its continuation, is simply reflective of the reality that we are
  the only primary palladium producer of scale in the world. Most of our
  competitors produce platinum as their primary metal and have no
  interest in promoting palladium at the expense of their principal
  product.
  
• Drastically reducing SG&A will impede our growth
  initiatives and thus our ability to create shareholder value.
  The Clinton Group has no experience managing a declining resource,
  expansion projects or mining at depth. Stillwater′s potential for
  value creation is a direct reflection of the way it invests in the
  business. We have prudently increased SG&A to support a stable and
  efficient annual PGM production target of 500,000 ounces per year and
  to put in place the necessary infrastructure to support our PGM growth
  initiatives. We have invested in growth and still operate at a much
  lower cost base than virtually all of our PGM peers.

YOUR BOARD HAS EXTENSIVE OPERATIONAL EXPERIENCE IN GLOBAL MINING AND
HAS ALREADY REVITALIZED STILLWATER TO BECOME THE LEADING NORTH AMERICAN
PGM PRODUCER

We have a skilled Board with significant operational and finance
experience in the mining industry and specifically within the countries
where we operate. We have also proactively brought fresh voices into our
Boardroom, adding two new directors with significant mining industry
experience in the last six months. Our management team, led by Frank
McAllister, has accomplished a significant turnaround of this business
over the past 12 years. Frank has guided a strategy that has brought the
Company from the verge of extinction when the palladium price collapsed
in 2001-2003 and positioned Stillwater as one of the most successful,
lowest-cost PGM producers in the world.

VOTE FOR THE STILLWATER NOMINEES ON THE WHITE
PROXY CARD TODAY

Protect the value of your investment. To supportyour Company′s
nominees, who are committed to looking after the best interests of ALL
Stillwater shareholders, please use your WHITE proxy card to vote TODAY?by
telephone, over the Internet, or by signing, dating and returning the WHITE
proxy card in the postage-paid envelope provided. You are urged to
discard any green proxy card sent to you by the Clinton Group. Even a
vote against the Clinton Group′s nominees on the Clinton Group′s green
proxy card will cancel any previous proxy submitted by you in favor of
Stillwater. Please vote only the WHITE proxy card.

We appreciate all the positive feedback we have received from our
shareholders, and thank you for your support.

Best regards,

/s/

Francis R. McAllister

Chairman and
Chief Executive Officer

Your Vote Is Important, No Matter How Many Or How Few Shares You Own

If you would like to obtain copies of the Company′s proxy materials or
have questions about how to vote your shares, or need additional
assistance, please contact the firm assisting us in the solicitation of
proxies:

INNISFREE M&A INCORPORATED

Shareholders Call
Toll-Free: (877) 825-8906

Banks and Brokers Call Collect:
(212) 750-5833

REMEMBER:

We urge you NOT to vote using any green proxy card
sent to you by

the Clinton Group, as doing so will revoke your vote
on the WHITE proxy card.

About Stillwater Mining Company

Stillwater Mining Company is
the only U.S. producer of palladium and platinum and is the largest
primary producer of platinum group metals outside of South Africa and
the Russian Federation. The Company′s shares are traded on the New York
Stock Exchange under the symbol SWC and on the Toronto Stock Exchange
under the symbol SWC.U. Information on Stillwater Mining Company can be
found at its website: www.stillwatermining.com.

Some statements contained in this news release are forward-looking
statements within the meaning of Section 27A of the Securities Act of
1933, as amended, and Section 21E of the Securities Exchange Act of
1934, as amended, and, therefore, involve uncertainties or risks that
could cause actual results to differ materially. These statements may
contain words such as 'believes,' 'anticipates,' 'plans,' 'expects,'
'intends,' 'projects?, 'estimates,' 'forecast,' 'guidance,' or similar
expressions. These statements are not guarantees of the Company's future
performance and are subject to risks, uncertainties and other important
factors that could cause our actual performance or achievements to
differ materially from those expressed or implied by these
forward-looking statements. Such statements include, but are not limited
to, comments regarding expansion plans, costs, grade, production and
recovery rates, permitting, financing needs, the terms of future credit
facilities and capital expenditures, increases in processing capacity,
cost reduction measures, safety, timing for engineering studies, and
environmental permitting and compliance, litigation, labor matters and
the palladium and platinum market. Additional information regarding
factors, which could cause results to differ materially from
management's expectations, is found in the section entitled 'Risk
Factors' in the Company's 2011 Annual Report on Form 10-K and in
subsequent filings with the United States Securities & Exchange
Commission. The Company intends that the forward-looking statements
contained herein be subject to the above-mentioned statutory safe
harbors. Investors are cautioned not to rely on forward-looking
statements. The Company disclaims any obligation to update
forward-looking statements.

Investors:

For Stillwater Mining Company

Mike Beckstead,
406-373-8971

or

Innisfree M&A Incorporated

Arthur
Crozier / Jennifer Shotwell / Scott Winter

212-750-5833

or

Media:

Sard
Verbinnen & Co

Dan Gagnier / Michael Henson

212-687-8080