Oolitic Aragonite Defined

what is oolitic aragonite?

Oolitic Aragonite sand is one of the world’s purest forms of the Ocean’s naturally precipitated calcium carbonate.  It has a crystalline morphology of orthorhombic, bipyramidal; characteristically needle-shaped crystals. The acicular needle-shape has a high aspect ratio giving aragonite one its strong practical advantages, and is formed by way of the biosequestration of Carbon Dioxide (CO2) created by the photosynthetic metabolism of cyanobacteria and microalgae, which freely flow in blooms over the Bahama banks.   This biogeochemical cycling of carbon in microbial precipitations of aragonite (CaCO3) replenishes at a rate of over 4 billion pounds per year.

formation of oolitic aragonite

The phenomenon in which oolitic aragonite is formed is described as a “Whitings” event.  Thought to be schools of fish disturbing the sandy bottom of the Bahama banks, “Whitings” are actually epicellular precipitation of calcium carbonate induced by photosynthesis in blooms of Picoplankton, predominantly cyanobacteria, that seasonally enter the shallow waters throughout the Bahamas.   In addition this photosynthesis and calcification process sequesters tens of thousands of tons of carbon dioxide from our environment.  Oolitic aragonite not only makes a cleaner environment in its generative process but also has the potential of helping to clean up the environment through its use in various industries, like plastics.

how aragonite formation sequesters carbon

Oolitic Aragonite is generated through the mineralization of Carbon Dioxide (CO2) to Calcium Carbonate (CaCO3) within natural occurring Blooms of phytoplankton, further picoplankton: specifically Cyanobacteria and unicellular green algea.  Photosynthesis drives the engine of both forms of carbon sequestration by cyanobacteria:

  1.   Reducing CO2 to organic compounds at the same time producing Oxygen (O2) through the Calvin-Benson-Bassham cycle.
  2. Mineralizing CO2 to recalcitrant carbonates; Calcium Carbonate (CaCO3).

Cyanobacteria has a Carbon Dioxide Concentrating Mechanism (CCM), a biochemical system that allows the cells to raise the concentration of CO2 at the site of the carboxylating enzyme rubulose (RUBISCO) up to 1,000 times surrounding medium.  Cyanobacteria excretes organic polymeric substances to form extracellular formations. These Exopolymeric substances (EPS) serve as a nucleation surface for mineralization.