In an article titled "Could putting pebbles on beaches help solve climate change?", Ben Houlton was interviewed by the SF Chronicle on the carbon sequestration potential of rocks:
"Project leader Ben Houlton, director of the John Muir Institute of the environment at UC Davis, said the study — funded with $5 million from California’s cap-and-trade program — uses a metabasalt taken from the tailings at a local mine and subjects it to the same weathering process as the beach project would, except on land.
Houlton said olivine was ruled out because it would poison the soil with heavy metals. The rock he uses was selected because it has potassium and zinc in it, which is good for crops. It is pulverized and mixed with the topsoil, where microbial activity causes the weathering that allows carbon dioxide to be consumed.
The idea, Houlton said, is to make the process healthful for crops and useful economically — crop yields have gone up 15% to 20% using the material — providing an incentive for sequestering carbon.
Houlton said his models have shown that farmers could capture between 5 and 10 billion tons of CO2 per year — a little less than a third of what is emitted worldwide — if 75% of earth’s croplands were treated this way.
“I think the capacity for a global scale solution is there,” he said, “but there is still a lot of progress to make on the science that is needed to validate this approach.”"
Follow the link to read more.