Calcium Carbonate Polyamorphism and Its Role in Biomineralization: How Many Amorphous Calcium Carbonates Are There?

TL;DR

This paper reviews the recent discovery of multiple amorphous calcium carbonate phases and their significance in biomineralization, offering new insights into polymorphic evolution and potential applications in various fields.

Contribution

It summarizes current knowledge on calcium carbonate polyamorphism and explores its role in biomineralization, highlighting new mechanistic insights.

Findings

Multiple amorphous calcium carbonate phases exist in biominerals.

Polyamorphism influences the evolution of calcium carbonate structures.

Understanding amorphous forms aids in controlling crystallization processes.

Abstract

Although the polymorphism of calcium carbonate is well known, and its polymorphs-calcite, aragonite, and vaterite-have been highly studied in the context of biomineralization, polyamorphism is a much more recently discovered phenomenon, and the existence of more than one amorphous phase of calcium carbonate in biominerals has only very recently been understood. Here we summarize what is known about polyamorphism in calcium carbonate as well as what is under- stood about the role of amorphous calcium carbonate in biominerals. We show that consideration of the amorphous forms of calcium carbonate within the physical notion of polyamorphism leads to new insights when it comes to the mechanisms by which polymorphic structures can evolve in the first place. This not only has implications for our understanding of biomineralization, but also of the means by which crystallization may be controlled in medical, pharmaceutical, and industrial contexts.