When the Crystal Bridges Museum of American Art opened a year ago in November, some critics harped on a major omission in its holdings. The collection barely represented the post-war period, a time when American artists came to influence the international art world.

A new acquistion begins to fill the gap in the museum's holdings. Abstract Expressionist Mark Rothko's "No. 210/No. 211 (Orange)," from 1960, was purchased in a private deal brokered by Christie's.

The work comes from a private Swiss collector and is said to be valued around $25 million.

Rothko prices have been rising. His"Orange, Red, Yellow," from 1961, fetched a record $86.9 million at Christie's, over an estimate of $45 million, last May.

The museum's Rothko will go on display on Oct. 13 in the special exhibition "See the Light: The Luminist Tradition in American Art." Nineteenth-century luminist landscapes will be shown with light-centered paintings by American Impressionists, modernists, and contemporary artists such as James Turrell.