It is also not unusual to see rhombohedra, whiskers, tubes, flowers and rosette particles of inorganic/organic materials in the nano- or micron-scale.
But, how about an Aspirin® pill-shaped, micron-size particle?
You know - round, with slightly out-curving sides; i.e., biconvex.
Never seen that kind of a precipitate?
Synthesis of monodisperse, biconvex pill-shaped microparticles, microtablets or micropills, precipitated directly from an aqueous solution, has not yet been reported for any natural or man-made materials.
Find a link here (A. C. Tas, Int. J. Appl. Ceram. Technol., 6, 53-59, 2009
to synthesize such micropills of CaCO3, which is a biocompatible and non-toxic material.
Such micropills may find numerous applications from biomaterials to electronics, and MEMS applications as well.
Contact: Prof. A. Cuneyt Tas, PhD firstname.lastname@example.org www.cuneyttas.com