Rockwood Holdings Inc. (NYSE: ROC) shares advanced 10% to $55.02 Wednesday, after the maker of specialty chemicals reported first-quarter results that topped analysts’ estimates. Volume for the stock topped 2.3 million shares by late afternoon.

Rockwood reported earnings per share from continuing operations of $0.80 for the first quarter of 2011 as compared to $0.42 for the same period in the prior year. The Company’s adjusted earnings per share increased to $0.88 in the first quarter of 2011 from $0.41 for the same period in the prior year.

Likewise, net sales were $914.0 million for the first quarter of 2011, up 17.4% compared to $778.4 million for the same period in the prior year.

According to the Company’s Chief Executive Officer, Seifi Ghasemi, “Rockwood’s exceptionally strong first quarter profits resulted from organic sales growth in all segments, as well as price increases that offset raw material and other cost increases. We were also able to improve our product mix, primarily in the specialty titanium dioxide business.”

“In addition,” Ghasemi continued, “our decision to repay a portion of our term debt and refinance the balance resulted in significantly lower interest expense, which further contributed to the significant increase in as adjusted earnings per share to $0.88 compared to the first quarter a year ago.”