**Donata Konopacka-Łyskawa**

Department of Process Engineering and Chemical Technology, Faculty of Chemistry, Gda ´nsk University of Technology, Narutowicza 11/12, 80-233 Gda ´nsk, Poland; donata.konopacka-lyskawa@pg.edu.pl; Tel.: +48-58-347-2910

Received: 15 March 2019; Accepted: 18 April 2019; Published: 25 April 2019

**Abstract:** Vaterite is the least thermodynamically stable anhydrous calcium carbonate polymorph. Its existence is very rare in nature, e.g., in some rock formations or as a component of biominerals produced by some fishes, crustaceans, or birds. Synthetic vaterite particles are proposed as carriers of active substances in medicines, additives in cosmetic preparations as well as adsorbents. Also, their utilization as a pump for microfluidic flow is also tested. In particular, vaterite particles produced as polycrystalline spheres have large potential for application. Various methods are proposed to precipitate vaterite particles, including the conventional solution-solution synthesis, gas-liquid method as well as special routes. Precipitation conditions should be carefully selected to obtain a high concentration of vaterite in all these methods. In this review, classical and new methods used for vaterite precipitation are presented. Furthermore, the key parameters affecting the formation of spherical vaterite are discussed.

**Keywords:** vaterite; calcium carbonate; polymorph; precipitation; synthesis; carbonation
