SM11A Preliminary Coring Results

22 March 2013

SM11A Preliminary Coring Results

§ Intersection from the deflection SM11A successfully cored through the shelf seam of polyhalite at mine site

§ 41.6 metres of 86% polyhalite (including 27.3 metres at 93%) intersected within a total length of 57.2 metres

§ Independent geologists SRK have confirmed they expect the results of SM11 and SM11A will support the upgrading of a significant portion of the Inferred Resource to the Indicated category

The Directors of Sirius Minerals Plc (AIM: SXX, OTCQX: SRUXY) ("Sirius" or the "Company") are pleased to announce the completion of coring of the deflection SM11A (the mine site) at the York Potash Project.

Drilling of SM11A commenced on 8 March 2013 following the completion of the parent hole SM11. Coring of the Fordon Evaporites commenced on 14 March 2013 from 1450.1m below rotary table (bRT) down to 1592.5m bRT. Polyhalite was intersected between 1507.69m and 1564.84m bRT. 41.6 metres of 86% polyhalite was intersected in three seams separated by two anhydrite bands with a combined intersected thickness of 15.6m. There was 100% core recovery.

The preliminary results show a strong correlation between SM11 and SM11A confirming the continuity of the orebody over mining distances which SRK expects will enable the upgrading of a significant portion of the current Inferred Resource to the Indicated Resource category. This will occur following the receipt of chemical analysis of the SM11 core which is expected at the beginning of May and the Resource upgrade to follow later that month.

Chris Fraser, Managing Director and CEO of Sirius said:

"The completion of this deflection and the strong correlation is a further endorsement of the quality and geological consistency of the York Potash polyhalite orebody. We look forward to the important upgrade to Indicated Resource in the near future."

Summary of Preliminary Results - SM11A (Collar: 489320 E, 505337 N; Ground Level 203.1m AOD)

Notes:

1. Rotary table is 4.99 m above ground level

2. Quoted grades and thicknesses are based solely on visual inspection of the core and geological interpretation of the Schlumberger spectral wireline gamma log, assuming that the potassium is present entirely as polyhalite. Assays are required to confirm the thickness and the polyhalite grades.

3. Borehole is deviated. Correction to seam thicknesses will be made once the core has been slabbed for assaying.

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About Sirius Minerals Plc

Sirius Minerals is a globally diversified potash development company. Its primary focus is to bring on stream major potash mining facilities through the acquisition and development of projects overlying recognised potash deposits. Today it holds properties in the United Kingdom (North Yorkshire), the United States (North Dakota), and Australia (Queensland). Incorporated in 2003, Sirius Minerals' shares are traded on the London Stock Exchange's AIM market. Its shares are also traded in the United States on the OTCQX through a sponsored ADR facility. Further information on the Company can be found at www.siriusminerals.com.

Qualified Persons

The information in this press release that relates to the geological model is based on information compiled under the direction of Dr Mike Armitage C Eng, who is a Member of the Institute of Materials, Minerals and Mining which is a 'Recognised Overseas Professional Organisation' (ROPO) included in a list promulgated by ASX from time to time.

Dr Armitage is a full time employee of SRK and has sufficient experience which is relevant to the style of mineralisation and type of deposit under consideration and to the activity which he has undertaken to qualify as a Competent Person as defined in the 2004 Edition of the 'Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves' (the JORC Code) and for the purposes of the AIM Rules. Dr Armitage has reviewed this press release and consents to the inclusion in the press release of the matters based on his information in the form and context in which this appears.

The information in this Stock Exchange Announcement that relates to drilling results, together with any related assessments and interpretations, have been verified by and approved for release by Dr Frederick W. Smith FIMMM., CEng, CSci, a qualified geologist and full-time employee of FWS Consultants Limited ("FWS"), Environmental and Geological Consultants. Dr Smith, who is a Fellow of the Institute of Materials, Minerals and Mining (IMMM), has sufficient experience which is relevant to the style of mineralisation and type of deposit under consideration and to the activity which he is undertaking to qualify as a Competent Person for the purposes of the AIM Rules. Dr Smith and FWS consent to the inclusion of the information contained in this announcement and the respective references to them in the form and context in which they appear.

Graham Clarke, Operations Director for Sirius Minerals Plc, who has reviewed this Stock Exchange Announcement, has over 26 years' experience in the potash mining industry. He has a Degree in Mining Engineering from the University of Nottingham, is a Fellow of the Institute of Materials, Minerals and Mining (IMMM) and extensive operational experience gained at Cleveland Potash Limited in the mining of the Boulby Potash seam and the exploration and development of the upper Fordon Polyhalite seam.