Amorphous calcium carbonate

ACC is extremely unstable under normal conditions and is found naturally in taxa as wide-ranging as sea urchins, corals, mollusks, and foraminifera.

ACC has been known to science for over 100 years when a non-diffraction pattern of calcium carbonate was discovered by Sturcke Herman, exhibiting its poorly-ordered nature.

[5] Research of such systems have diverse application; however, the current lack of unambiguous answers to fundamental questions (i.e. solubility product, interfacial forces, structure, etc.)

causes them to be topics of study in fields ranging from chemistry, geology, biology, physics, and materials science engineering.

For example, the American Lobster Homarus americanus, maintains stable ACC throughout its yearly molt cycle.

[2][9] ACC is widely used by crustaceans to stiffen the exoskeleton as well as to store calcium in gastroliths during the molt cycle.

[12][13] Also, ACC crystallisation pathways have been observed to depend on its Mg/Ca ratio, transforming to aragonite,[14] Mg-calcite,[15] monohydrocalcite[16] or dolomite[17] with increasing Mg content.

[24] In this method CaO is dispersed in methanol under a pressure of carbon dioxide in a sealed reaction vessel.

Also improving framework material development for CO2 capture, H2 storage, emissions control, biomass conversion, molecular separations, and biofuel purification.