PRINCETON, NJ – Rockwood Holdings Inc. has entered into a definitive agreement to sell its Clay Based Additives business to ALTANA Group, Wesel, Germany, a global specialty chemical company. The purchase price is $635 million, subject to customary adjustments.

 A segment of Rockwood’s Performance Additives business, Clay Based Additives had 2012 sales of $191.4 million. This transaction is expected to close during the fourth quarter of 2013 following receipt of certain regulatory approvals.

With the acquisition, ALTANA is expanding its existing additives portfolio. The company plans to integrate the business into its BYK Additives & Instruments division. The acquisition adds four production sites to the company: Gonzales (Texas), Louisville (Kentucky), Widnes (UK) and Moosburg (Germany).