Daniel Hummer, right, of the Carnegie Institution for Science, talks with Jack Howell about the Carbon Mineral Challenge during The Tucson Gem and Mineral Show at the Tucson Convention Center on Thursday February 11, 2016. The Deep Carbon Observatory is funding a project that is challenging collectors to find 145 carbonaceous rocks that mathematically are predicted to exist. Hummer says the challenge started in December and already two have been located, there are 143 left. The project is funded through 2019.

Mamta Popat / Arizona Daily Star

The world’s collectors come to Tucson each February, seeking to add a gem, fossil or rock to their collections.

Some geologists, meanwhile, are collecting rockhounds — enlisting those collectors in a challenge to complete the mathematical map of carbon-bearing minerals.

The theoretical map of undiscovered minerals is based on work done at the UA, led by Robert Downs, to compile an open-access database of minerals.

Downs used a statistics-based computer model to predict the missing minerals.

There are 406 known carbon minerals, and an average of four have been discovered each year in the past five years.

Mineralogists want to accelerate discovery and have issued a Carbon Mineral Challenge to find the 145 carbonaceous undiscovered rocks that are mathematically predicted to exist.

Downs, curator of the UA Mineral Museum, along with other UA geoscientists, will help provide analysis of the candidate rocks.

Daniel Hummer of the Carnegie Institute for Science is leading the Carbon Mineral Challenge. He set up a table Thursday at the Tucson Gem and Mineral Show to pass out information on the quest for new minerals.

Hummer said the amateur and professional mineralogists who attend the gem show know when they have something that might be unusual. He expects that some of the undiscovered rocks reside in private or even museum collections.

Hummer said those who find the minerals, along with the researchers who analyze them, will have a say in the naming of the rocks.

Hummer, a post-doctoral scholar at Carnegie, said he’d like to put his own name on a rock some day, although there is already a “hummerite” in the catalog.

Hummer said carbonaceous minerals are an important part of the geology of Earth and the source of life itself. “Life is based on carbon chemistry,” he said.

Contact reporter Tom Beal at tbeal@tucson.com or 573-4158.