Thousands of people are gathering in Tucson this week to take part in what is described as the largest treasure hunt in the world.

Although it's usually referred to as the Gem and Mineral Show, the event is actually made up of dozens of shows from many organizations as part of The Gem, Mineral and Fossil Showcase.

Paul Harter is a member of the Tucson Gem and Mineral Society, and he says a small and simple event that expanded and began to flourish decades ago has become the largest gathering of its kind in the world.

Today, it is considered a brilliant cultural and economic gem for Tucson and the state.

"A group of guys would go out and collect minerals on the weekend and they decided we ought to have a club, and the club morphs into the Tucson Gem and Mineral Society," Paul Harter says.

"Fifty-nine years ago, group members said, 'we ought to have a show'," Harter said. "It was such a success, they said, 'let's have a second show.'"

The Gem, Mineral and Fossil Showcase is being held all over the metropolitan area through Feb. 17.

The big spectacle, the Tucson Gem and Mineral Society's 59th annual event, will be at the Tucson Convention Center Feb. 14 through 17.