Growth and characterization of calcium oxalate dihydrate crystals (weddellite).

Conditions are given for the growth of calcium oxalate dihydrate crystals (weddellite) in aqueous solution. The crystals obtained were characterized by scanning electron microscopic, spectroscopic, and thermal methods. The dissolution kinetics and electrophoretic mobility were determined; the thermodynamically unstable calcium oxalate dihydrate had a higher dissolution rate and a lower zeta potential than the monohydrate and underwent a phase transformation into the more stable calcium oxalate monohydrate. The results obtained on the chemical stability and the surface charge of calcium oxalate dihydrate offered additional information for assessing the current theories on the formation of calcium oxalate renal stones.