RENO, Nevada (AP) — Charles B. Gillespie's iconic California Gold Rush artwork is no longer a family secret.

Historians are hailing the obscure 49er's extensive collection of sketches and oil paintings after a descendant decided to put it up for sale this fall. "This is an important archive, particularly the sketches, which are charming and historically significant," Scott Shields, chief curator of the Crocker Art Museum in Sacramento, California, says.

For decades, the pieces were tucked away in the home of Gillespie's great-great grandson, Dick Rogers of Bowling Green, Ohio.

Now, Rogers is working with a Reno dealer, Fred Holabird, to try to sell the collection to a museum so the public can finally have a chance to view it.

It's one of the most important Gold Rush archives to surface in the last 100 years, says Holabird, president of Reno-based Holabird-Kagin Americana, one of the country's largest sellers of Western Americana. "It's a remarkable, wonderful archive, and it gave me goose bumps the first time I saw it," he says. Historians say the collection is valuable primarily because it captures California's seminal event: James Marshall's 1848 discovery of gold at Sutter's Mill in Coloma.

The collection is unique for its sheer size as very few gold seekers drew more than a handful of sketches on overland journeys, says Peter Blodgett, curator of manuscripts at the Huntington Library in San Marino.

Though Gillespie operated a studio in Pittsburgh as a young adult, he never received formal art instruction. He died in 1907 at age 86 after a career as a physician.

Gillespie maintained a lifetime passion for art, painting Eastern scenes as well as portraits of family members and himself. He never sold any of his works.