Magnesita Refratarios : Material Fact - Admission of RHI-MAG shares on the London Stock Exchange

MAGNESITA REFRATÁRIOS S.A.

CNPJ (Corporate Taxpayer Registry) no. 08.684.547/0001-65 NIRE (Commercial Registry Number) 31.300.026.485

MATERIAL FACT

Magnesita Refratários S.A. ("Company"), pursuant to the terms of Law no. 6,404/76 and Rule no. 358/02 of Comissão de Valores Mobiliários ("CVM"), hereby informs its shareholders and the market in general and in connection with the transaction disclosed in the Material Fact dated October 5, 2016, by which Alumina Holdings, LLC ("Alumina"), Rearden L. Holdings 3 S.À R.L. ("Rearden" and, jointly with Alumina, "Controlling Shareholders of Magnesita") and RHI AG ("RHI") signed an agreement with the purpose of combining the operations of RHI and the Company to create a leading company in refractory solutions, named RHI-MAG N.V. ("RHI-MAG") ("Transaction"):

On the date hereof, the Company was informed by RHI that another important condition precedent to the completion of the Transaction was completed, i.e., the Dutch Authority for the Financial Markets approved today the prospectus for (1) admission to listing of RHI-MAG shares on the premium listing segment of the Official List of the UK Financial Conduct Authority ("Admission") and (2) trading on the London Stock Exchange's main market for listed securities ("Trading").

In addition to the information disclosed in the Material Fact dated October 5, 2016, the Company was informed by RHI the following:

1. Following completion of the Transaction, pursuant to Law No. 6.404/76, the regulations of the CVM and to the Listing Rules of the Novo Mercado Segment of the Brazilian Stock Exchange (B3 S.A. - Brasil, Bolsa, Balcão), RHI-MAG or one of its affiliates will launch a mandatory tender offer to acquire the remaining shares issued by the Company ("OPA").The OPA will be directed to all the shareholders of the Company on the same terms and conditions, including consideration per share and form of payment (i.e. RHI-MAG shares and cash), as those offered to the Controlling Shareholders of Magnesita under the Transaction. Nevertheless, the 12-month lock-up period of the RHI-MAG shares will no longer be applicable to all the OPA offerees, but only to the Controlling Shareholders of Magnesita.

2. The Controlling Shareholders of Magnesita have been released from their commitment to purchase additional new RHI-MAG shares (in case some or all of the Company's remaining shareholders elect not to receive RHI-MAG shares in the OPA).

Completion of the Transaction is expected to occur on October 26, 2017, Admission and Trading on October 27, 2017.The Company will keep its shareholders and the market in general informed regarding the completion of the Transaction.

São Paulo, October 17, 2017.

Otavio Augusto Castro Lustosa Nogueira Financial and Investors' Relations Officer Magnesita Refratários S.A.