Bob Beeston, the Chairman of FTSE 250 specialty chemicals group Elementis, is to step down from the board at the end of the month for personal reasons, the company announced on Monday.Elementis said that Senior Independent Director Ian Brindle will be interim Chairman while the board continues to look for Beeston's successor.Markets reacted positively to the statement in morning trade, with the share price up 0.64% at 234.3p early on.Beeston was appointed as the firm's Non-Executive Chairman back in September 2006 and has held board positions at other UK-listed heavyweight companies in the past, including Cookson, DS Smith and FKI.Brindle said: "[Beeston] has led the board through a period in which the company has experienced significant positive change and the foundations of its growth strategy were laid. "On behalf of the board, I would like to express my sincere thanks to Bob for his leadership and wise counsel over the years and wish him a happy retirement."The firm also announced Chris Girling's decision to retire from the board and step down as Chairman of the audit committee. He will be replaced by Non-Executive Director Anne Hyland, who joined the company just last month.Elementis operates through three main businesses: Specialty Products, Surfactants and Chromium. Through these divisions, the company serves a wide variety of markets, producing additives for paints, cosmetics and oil & gas exploration, as well as providing chemicals used in aerospace alloys, timber treatment and leather production.BC