Mineral sequestration is the formation of carbonate salts by reaction of bicarbonate with dissolved calcium and magnesium. This process occurs slowly in nature and is responsible for the deposition and accumulation of limestone. A somewhat faster than natural reaction occurs when dunite, or its hydrated equivalent serpentinite, react with carbon dioxide to form the carbonate mineral magnesite, plus silica and iron oxide (magnetite). Serpentinite sequestration is favored because of the non-toxic and predictable nature of magnesium carbonate. The ideal reaction involves extremely magnesium-rich olivine or serpentine minerals. The presence of iron in the olivine or serpentine can produce silica or magnetite slag.

All sequestration techniques involve extensive monitoring, mitigation and verification (MMV) and continuous risk assesment of the site. Effective application of proper MMV procedures will ensure the saftey of carbon sequestration techniques with regards to human and environmental health.

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