Sirius Minerals Regulatory News (SXX)

23 January 2012

Sirius Minerals Plc

("Sirius" or the "Company")

SM2 Preliminary Coring Result

§ Two distinct seams of overlapping massive polyhalite intersected

§ 67 metres of total massive polyhalite mineralisation across the hole

§ 33 metres of massive polyhalite in the materially shallower "Shelf" bed that is currently being mined at the Boulby Mine

§ 34 metres of massive polyhalite in the deeper "Basin" bed, as encountered at SM1

The Directors of Sirius Minerals Plc (AIM: SXX, OTCQX: SRUXY), the globally diversified potash development group, are pleased to announce the completion of coring at SM2, the second new borehole completed at the York Potash Project.

Chris Fraser, Managing Director and CEO of Sirius said:

"We are delighted SM2 has delivered another world-class and very significant result for the York Potash Project. The confirmation of two thick and potentially high grade seams, the upper or "Shelf" seam and the lower or "Basin" seam, present us with the exciting possibility of sinking the mine shafts only to the shallower Shelf seam, which would potentially lower the shaft's construction costs and shorten the construction time. This presents an opportunity to significantly improve the project's economics and value to shareholders.

"An important element of our drilling programme has been to add information to, and refine, our interpretation of the deposit and the nature of the polyhalite beds within it. This hole, which we believe to be in the transition zone between the Fordon Evaporite Shelf and Basin, confirms the existence in this area of two overlapping seams of massive polyhalite."

Completion of SM2 Coring

Drilling of SM2 (Howlet Hall) commenced on 2 September 2011, with a successful change from the smaller top-hole rig (which then moved onto SM3) to the larger coring-rig on 8 November 2011. As announced to the market, a series of fluid-loss-zones were encountered during the drilling of the section between about 947 and 1,175m. This slowed the progress of this hole as each loss zone was repaired to enable drilling to proceed. Due to the delays and ongoing losses the decision was made to not core the Boulby and Sneaton sylvite seams. Coring of the critical Fordon Evaporite section was commenced on 13 January 2012 and successfully completed on 21 January 2012, proceeding from 1,412 metres to 1,598 metres below surface with 100% recovery; fully justifying the time and care taken earlier.

Two distinct massive polyhalite seams have been successfully cored. The first in the upper near-shore facies (i.e. depositional environment) of the Fordon Evaporites (the "Shelf"), and then approximately 82m below that, a lower massive polyhalite seam apparently correlating with that intersected at SM1 (drilled further into the heart of the Fordon Basin). The intervening strata consist of mostly very low grade polyhalite mineralisation, containing occasional bands of massive polyhalite with individual thicknesses of up to 1.5 metres (these have not been included in this Summary).

The table below gives preliminary results based on visual examination of the cores in the field. Detailed results will be provided following wireline logging of the borehole, examination of the core under laboratory conditions, mineralogical and chemical analysis.

Summary Preliminary Results - SM2 (collar: 488424.89 E, 506841.87 N, 143.22m AOD)

Notes:

1. Depth from sea-level shown due to the varying topography of the York Potash drill sites.

2. Thickness based solely on visual and geological interpretation of the key mineralised zones. Full chemical assays are required to confirm the thickness interpretation and the potassium grades of the mineralisation.

3. "Massive polyhalite rock" refers to the visual interpretation of the cores as being apparently high purity polyhalite. However, grade can only be confirmed with the completion of the full chemical assays.

Preliminary Geological Interpretation

A significant amount of historical data provides the foundation for our geological model. The western edge of the Fordon Basin is known to have been a shallow-water depositional "shelf" in Permian times, in which a condensed sequence of evaporites was deposited. Numerous holes have been drilled through the shelf for gas exploration, and these repeatedly demonstrated the existence of a thick, relatively high grade (based on gamma logs), polyhalite seam.

The main part of the Fordon Basin, as explored by SM1 and historical boreholes, is believed to have been a deeper-water "basinal" depositional environment. It also contains a thick, high grade, deposit of massive polyhalite towards the bottom of the sequence. This was confirmed in SM1, where Sirius intersected the seam, which included an aggregated thickness of 23.3 metres (true-thickness) of 95% polyhalite (27.5% K2SO4).

Prior to completion of SM2 there were two theories as to the nature of the transition zone between these two high grade beds. One was that they were effectively the same bed that was "draped" over the ramp zone interface between the shelf and basin areas. The second theory was that they were two separate but broadly contiguous beds. It is our current belief that SM2 has proved that the second theory of the structure is correct. Moreover SM2 has proved that in this part of the transition zone there are two beds of massive, apparently high grade, polyhalite, approximately 82m vertically apart and that these appear to represent overlapping "shelf" and "basinal" beds.

The implications of this are being analysed, but it is clear that there is potential to construct the shafts down to the shallower (i.e. closer to surface) "Shelf" seam and that this represents a potential to significantly improve the value of the York Potash Project. At a depth from surface of approximately 1,420m, the potential to reduce the costs of the shafts and reduce the construction timeframes of the project are significant. Alan Auld Group, the engineering firm working on shaft designs for York Potash, is now factoring this into the reports it is preparing for inclusion in the Detailed Scoping Study.

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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 and Western Australia).

The Company is additionally progressing ongoing innovation initiatives into the secondary uses of salt and potash beds for energy storage and carbon dioxide sequestration.

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 the use of a sponsored ADR facility. Further information on the Company can be found at www.siriusminerals.com.

Competent Person's Statement and Risk Statement

The information in this Stock Exchange Announcement that relates to Mineral Exploration results and Exploration Targets, 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. The JORC Exploration Target estimates of quantity and grade are conceptual in nature and there has been insufficient exploration to define a Mineral Resource on the property and it is uncertain if further exploration will result in discovery of a Mineral Resource on the Property. The estimates are not a Reserve or Resource statement in accordance with an AIM recognised Standard and should not therefore be relied upon as such. It should be noted that the Pan European Code of Reporting or PERC (that IMMM co-wrote) released in December 2008 and JORC are essentially identical on all key aspects relating to compilation and quoting Exploration Targets.