PROVO — Historians believe Brigham Young sat for two photographs taken by Salt Lake City's lone commercial daguerreotypist during a single sitting in 1852, '53 or early '54.

The images captured that day are two of the five earliest-known images of Young, and one of them is now in the possession of the school that bears his name, Brigham Young University.

One of the fragile daguerreotypes is on display in the National Portrait Gallery at the Smithsonian. Daguerreotype detectives like BYU historian Richard Holzapfel feared the other had been damaged and thrown away or was otherwise lost or destroyed until Bountiful residents Mark and Suzanne Richards donated it to BYU in December.

"This is a rare item. My guess is that it has to be worth at least $25,000 to $40,000," said Holzapfel, co-author of "Brigham Young, Images of a Mormon Prophet."

Historians knew one of Young's daughters gave the daguerreotype to Richards' grandfather Preston Nibley in the 1930s. Nibley included the image in a 1936 biography titled "Brigham Young, The Man and His Work."

Nibley died in 1966, and Richards was 16 when his grandmother died in 1980 and the daguerreotype passed to him.

"When I first got it, I didn't realize it had as much value as it does," Richards said. "The last few years, as I learned more about daguerreotypes, I thought it probably would have a lot of historical value."

An appraiser told Richards last year that the photo was worth $25,000. He decided his grandfather, who was an official LDS Church historian from the mid-1940s to the early 1960s, wouldn't want him to sell it. His thoughts turned to BYU even though he never attended the university.

"I thought because of the name of the university and its affiliation with the church and the special collections facility they have at the Lee Library, BYU was a good place to donate it so if anyone else wanted access, they could have it," he said.

This image of Young was nationally known in June 1854, when a woodcutting of it appeared in an issue of what Holzapfel described as the People magazine of the day. Young was one of the most famous Americans of the 19th century, a polygamist who led the Mormon exodus to the Utah desert. Sales of copied photographs of Young in the 1860s and '70s rivaled those of Abraham Lincoln and Civil War generals.

"Mormons were a curiosity," Holzapfel said.

Today, daguerreotypes are a curiosity. Invented by Frenchman Louis Daguerre in 1839, they were created by coating one side of a thick copper plate with silver, buffing the silver coating to a mirror finish, sensitizing it to light and exposing it in the camera. The result was like a Polaroid, a unique image that couldn't be reprinted like prints from a negative.