22 September 2017

                     THIS ANNOUNCEMENT CONTAINS INSIDE INFORMATION                 

                                   Acacia Mining plc                               

                                        LSE:ACA                                    

                      ("Acacia" or the "Company" or the "Group")                   

                    Positive Results from Buzwagi Processing Trial                 

    Acacia is pleased to announce positive results from the processing trial
    underway at Buzwagi that has been designed to maximise gold doré production
    from the mine.

    Buzwagi currently produces both doré (gold bars) and a gold/copper concentrate
    (with over 90% of the value of the concentrate being gold). During 2017, gold/
    copper concentrate has accounted for approximately 65% of Buzwagi's gold
    production. Since 3 March 2017, however, the mine has been unable to export and
    sell its concentrate, and as such has only been selling approximately 35% of
    its gold production, whilst incurring 100% of the cost of production.

    The results of the processing trial to date have indicated that Buzwagi should
    be able to achieve gold recoveries of around 85% through the additional use of
    reagents in the leaching circuit at limited additional operating costs. All of
    the recovered gold will be produced in doré form. Buzwagi previously intended
    to end concentrate production in Q2 2018, but as a result of the trial the mine
    will solely produce doré from now until the end of its life in 2020.

    There are no changes to group production or cost guidance resulting from this
    processing change, however it will result in Buzwagi being able to sell an
    additional 8,000-10,000 ounces per month for the remainder of the year. As
    such, Government royalties and local service levies (which are based on
    revenue) from Buzwagi are expected to more than double for the remainder of the
    year due to the increase in sales compared to the last 6 months. We believe
    that the changes will move the mine from a monthly cashflow negative position
    to a monthly cashflow positive position, strengthening Acacia's balance sheet
    and helping to protect thousands of direct and indirect jobs that the Company
    supports.

    ENQUIRIES

    For further information, please visit our website: www.acaciamining.com or
    contact:

    Acacia Mining plc                          +44 (0) 20 7129 7150
    Giles Blackham, Investor Relations  

    Camarco                                      +44 (0) 20 3757 4980
    Gordon Poole / Billy Clegg / Nick Hennis

    About Acacia Mining plc

    Acacia Mining plc (LSE:ACA) is Tanzania's largest gold miner and one of the
    largest producers of gold in Africa. We have three mines, all located in
    north-west Tanzania: Bulyanhulu, Buzwagi, and North Mara and a portfolio of
    exploration projects in Kenya, Burkina Faso and Mali.

    Acacia is a UK public company headquartered in London. We are listed on the
    Main Market of the London Stock Exchange with a secondary listing on the Dar es
    Salaam Stock Exchange. Barrick Gold Corporation is our majority shareholder.
    Acacia reports in US dollars and in accordance with IFRS as adopted by the
    European Union, unless otherwise stated in this announcement.

    Disclaimer and forward-looking statements

    This announcement is for information purposes only and does not constitute an
    invitation or offer to underwrite, subscribe for or otherwise acquire or
    dispose of any securities of Acacia in any jurisdiction.

    This announcement includes "forward-looking statements" that express or imply
    expectations of future events or results as opposed to historical facts. These
    statements include, financial projections and estimates and their underlying
    assumptions, statements regarding plans, objectives and expectations with
    respect to future production, operations, costs, projects, and statements
    regarding future performance. Forward-looking statements are generally
    identified by the words "plans," "expects," "anticipates," "believes,"
    "intends," "estimates" and other similar expressions.

    All forward-looking statements involve a number of risks, uncertainties and
    other factors, many of which are beyond the control of Acacia, which could
    cause actual results and developments to differ materially from those expressed
    in, or implied by, the forward-looking statements contained herein. Factors
    that could cause or contribute to differences between the actual results,
    performance and achievements of Acacia include, but are not limited to, changes
    or developments in political, economic or business conditions or national or
    local legislation or regulation in countries in which Acacia conducts - or may
    in the future conduct - business, industry trends, competition, fluctuations in
    the spot and forward price of gold or certain other commodity prices (such as
    copper and diesel), currency fluctuations (including the US dollar, South
    African rand, Kenyan shilling and Tanzanian shilling exchange rates), Acacia's
    ability to successfully integrate acquisitions, Acacia's ability to recover its
    reserves or develop new reserves, including its ability to convert its
    resources into reserves and its mineral potential into resources or reserves,
    and to process its mineral reserves successfully and in a timely manner,
    Acacia's ability to complete land acquisitions required to support its mining
    activities, operational or technical difficulties which may occur in the
    context of mining activities, delays and technical challenges associated with
    the completion of projects, risk of trespass, theft and vandalism, changes in
    Acacia's business strategy and ongoing implementation of operational reviews,
    as well as risks and hazards associated with the business of mineral
    exploration, development, mining and production and risks and factors affecting
    the gold mining industry in general.

    Although Acacia's management believes that the expectations reflected in such
    forward-looking statements are reasonable, Acacia cannot give assurances that
    such statements will prove to be correct. Accordingly, investors should not
    place reliance on forward-looking statements contained in this announcement.
    Any forward-looking statements in this announcement only reflect information
    available at the time of preparation. Save as required under the Market Abuse
    Regulation or otherwise as may be required under applicable law, Acacia
    explicitly disclaims any obligation or undertaking publicly to update or revise
    any forward-looking statements in this announcement, whether as a result of new
    information, future events or otherwise. Nothing in this announcement should be
    construed as a profit forecast or estimate and no statement made should be
    interpreted to mean that Acacia's profits or earnings per share for any future
    period will necessarily match or exceed its historical published profits or
    earnings per share.