The share price of potash development group Sirius Minerals took a dive Monday morning as talks with Sino-Agri Mining about jointly exploiting Sirius's wholly owned Adavale project drag on.Discussions between the two parties are continuing but they will have to crack on if a deal is to be signed before the expiration of the exclusivity period runs out on 15 February.Sirius said the memorandum of understanding between the two companies will remain in place even after the expiration of the exclusivity period. The directors of Sirius remain committed to building a long-term mutually beneficial partnership with Sino-Agri and more broadly with China.In an operational update, the company said that the integration of the York potash project, acquired on 17 January, is proceeding well, with the project moving ahead of many fronts, including the continued acquisition of mineral rights within the project area, the selection of suitable drilling locations and preliminary analysis of possible operating and capital cost structures. Meanwhile, at its Canning Basin project, studies have progressed well on the Southern tenements but material progress on the Northern tenements has not yet been made.