Enhanced mineral weathering is the process by which damp fresh igneous rock surfaces react with carbon dioxide to make calcite and other minerals.

In the UK, a major source is the fine dust produced as a side project when crushing certain igneous rocks in quarries. Heaped up, these stockpiles weather slowly, but spread 30cm thick on green verges, they weather extremely quickly.

They are however localised heavy, need fuel to transport, and energetic to make for this purpose alone.