SALT LAKE CITY — The Mormon church for the first time is publishing photos of a small sacred stone it believes founder Joseph Smith used to help translate the story that became the basis of the religion.

The pictures of the smooth, brown, egg-sized rock are part of a new book that also contains photos of the first printer’s manuscript of the Book of Mormon. Officials with The Church of Jesus Christ of Latter-day Saints unveiled it Tuesday at a news conference in Salt Lake City.

It’s the religion’s latest step in a push to be more transparent about its history and tenets. The church’s effort in recent years to be more open about its past was triggered by the religion’s increasing prominence as its membership tripled over the past three decades to 15 million worldwide today. Questions emerged about the burgeoning faith, with some criticizing it for being secretive about its beliefs and practices.

Mormons believe that 185 years ago, Smith found gold plates engraved with writing in ancient Egyptian in upstate New York. They say that God helped him translate the text using the stone and other tools, which became known as the Book of Mormon.

The pictures in the new book show different angles of a stone that is dark brown with lighter brown swirls, the size and shape of an egg. The photos also show a weathered leather pouch where the stone was stored that is believed to be made by one of Joseph Smith’s wives, Emma Smith.

The church has always possessed the stone, which was transported across the country during Mormon pioneers’ trek from Illinois to Utah in the mid-1800s, but it decided to publish the photos now to allow people who prefer visuals to words to better understand the religion’s roots, said Richard Turley, assistant church historian. The stone will remain in the vault.

“The picture brings a kind of tangibility to something that has been previously been talked about just in words,” Turley said. “That helps people connect with the past. We’ve discovered that artifacts and historical sites are a way to give a sense of reality to things that are otherwise somewhat ethereal.”

The church has been releasing books containing historical documents that shed light on how Smith formed the church. The religion also has issued a series of in-depth articles that explain or clarify some of the more sensitive parts of its history that it once sidestepped, such as the faith’s past ban on black men in the lay clergy and its early history of polygamy.

The ubiquitous use of the Internet today, and accompanying searches about the faith’s roots, tenets and beliefs, have also played a factor in the church’s decision to open more of its vault.

“The Internet brings both challenge and opportunities,” said Steve E. Snow, church historian. “We’re grateful for the opportunity to share much of collection through the use of the Internet.”