[ by Melanie Gretchen ] An unusually large number of Goldman partners left the firm in 2011, and that trend has carried over into early 2012.  The latest partner to "retire," according to people briefed on the matter, is senior deal maker, George Mattson.  Mr. Mattson, a co-head of Goldman’s global industrials group, heads out amid Q4 earnings of $978 million - a decline of nearly 56% from the period a year earlier. Mattson's departure couldn't have been a surprise to Goldman senior management, because early Monday the firm announced his replacement - Dusty Philip, with Clare Scherrer as the group’s COO. Mr. Mattson joined Goldman Sachs in 1994. During his career at the Wall Street bank, he held several top positions within the firm’s investment banking unit, sitting on both its operating and its client and business standards committees.  At Goldman, his clients have included General Motors, General Electric, the United Parcel Service, and Caterpillar.  He is a graduate of Duke University and the Wharton School at the University of Pennsylvania. Goldman partnership population: 450 and counting (down). For more details, go to [Dealbook, 2/13/12] and [Dealbook, 2/13/12].