IAMGOLD Corporation today announced the first mineral resource estimate in accordance with the Canadian Institute of Mining, Metallurgy and Petroleum ("CIM") Definition Standards incorporated by reference in National Instrument 43-101 ("NI 43-101") for the Saramacca deposit located approximately 25 kilometres from its Rosebel operation in Suriname.

The resource estimate comprises 14.4 million tonnes of indicated resources averaging 2.20 grams of gold per tonne for 1,022,000 ounces and 13.6 million tonnes of inferred resources averaging 1.18 grams of gold per tonne for 518,000 ounces. Approximately 60% of the resources are contained within shallow, softer laterite and saprolite hosted mineralization. The Saramacca deposit remains open along strike in both directions and at depth and has significant potential for expansion.

IAMGOLD's President and CEO, Steve Letwin, commented, "The NI 43-101 maiden resource estimate for Saramacca confirms the significance of this gold discovery, and adds to the substantial resource increase reported at Rosebel just over a month ago. With an estimate surpassing our expectations and a deposit that remains open, our transformative strategy to consolidate prospective land packages around Rosebel continues to add significant value for IAMGOLD shareholders."

Craig MacDougall, Senior Vice President, Exploration for IAMGOLD, stated, " The initial resource estimate reported for the Saramacca deposit today is the culmination of an outstanding effort by our exploration and support teams, who have worked tirelessly to advance the project since the commencement of exploration activities last September. These initial results not only exceed our expectations, but we are excited about the potential to further expand the current resources and to make additional discoveries on the property. I congratulate the exploration team for the well-executed and safely-completed exploration program leading to today's announcement."

The mineral resource for the Saramacca deposit incorporates assay results from 307 diamond and reverse circulation drill holes spaced at approximately 50 x 50 metres and totalling approximately 47,000 metres, including 217 holes totalling 37,700 metres completed by IAMGOLD. The estimate was prepared using a block model constrained with 3D wireframes of the principal mineralized domains. Values for gold were interpolated into blocks using ordinary kriging (OK). An open pit optimization algorithm was run on the block model to constrain the resource and to support the CIM requirement that Mineral Resources have 'reasonable prospects for eventual economic extraction'. The resource estimate assumes a long-term gold price of US$1,500/ounce. Only mineralization contained within the preliminary pit shell has been included in the resource estimate. It is meaningful to note that the pit shell generated extends to the base of the defined resources in some of the higher grade zones of the deposit. The effective date of this resource estimate is August 28, 2017.

The Saramacca project is strategically located approximately 25 kilometres southwest of the Rosebel Gold Mine processing facility. Mineralization is hosted in the Paramaka Formation within the lower part of the Marowijne Greenstone Belt, which is dominated by metamorphosed basalt and andesite lithologies in the project area. These are traversed by the regional, northwest trending Saramacca shear zone, an important deformation zone for the localization of gold mineralization. Drilling has confirmed the presence of multiple mineralized structures within an approximately 2-kilometre long and 400-metre wide corridor. Mineralization occurs in the near surface oxidized weathering profile to depths ranging from 50 to 100 metres, as well as deeper in primary sulphide zones. In the deposit area, three mineralization styles are recognized from the drilling completed to date: breccia hosted mineralization characterized by jigsaw, crackle and matrix supported breccias; shear hosted mineralization characterized by well-developed pyritic disseminations and stringers; and irregular pyrite-quartz-carbonate veins which locally carry high gold grades.

On August 30, 2016, the Company signed a letter of intent with the Government of Suriname to acquire rights to the Saramacca property, with the intent of defining a National Instrument 43-101 mineral resource within 24 months. The terms of the letter included an initial payment of $0.2 million, which enabled immediate access to the property for Rosebel's exploration team to conduct due diligence, as well as access to the data from previous exploration activity at the Saramacca property. On September 30, 2016, having been satisfied with the results of the due diligence, the Company ratified the letter of intent to acquire the Saramacca property and subsequently paid $10 million in cash and agreed to issue 3.125 million IAMGOLD common shares to the Government of Suriname in three approximately equal annual instalments on each successive anniversary of the date the right of exploration was transferred to Rosebel (December 2016). In addition, the agreement provides for a potential upward adjustment to the purchase price based on the contained gold ounces identified by Rosebel in National Instrument 43-101 measured and indicated resource categories, within a certain Whittle shell within the first 24 months, to a maximum of $10 million.

The Saramacca project falls within the "UJV" area as defined in an Agreement with the Government of Suriname announced on April 15, 2013. The Agreement establishes a joint venture growth vehicle under which Rosebel would hold a 70% participating interest and the Government will acquire a 30% participating interest on a fully-paid basis.