Table 1. Experimental Conditions and Calcium Carbonate Precipitate Characteristics^a.

sample	conc. of Ca2+ (M)	conc. of urea (M)	time (h)	phaseb (% of crystals)
1	0.15	0.15	24	88% C–12% V
2	0.25	0.25	24	55% C–45% V
3	0.35	0.35	24	40% C–60% V
4	0.50	0.50	24	40% C–60% V
5	0.65	0.65	24	39% C–61% V
6	0.75	0.75	24	43% C–57% V
7	0.85	0.85	24	42% C–58% V
8	1	1	24	40% C–60% V
9	0.5	0.5	0.15	98% C–2% V
10	0.5	0.5	1	87% C–13% V
11	0.5	0.5	10	69% C–31% V
12	0.5	0.5	15	52% C–48% V
13	0.5	0.5	24	40% C–60% V
14	0.5	0.5	72	50% C–50% V
15	0.5	0.5	30 days	90% C–10% V
16	0.5	0.5	2 yearsc	40% C–60% V

^aFor all samples, the pH of the biomineralization solutions was set at 9.0 and the temperature was maintained at 30 °C throughout the experimental duration.

^bAbbreviations: V, vaterite; C, calcite.

^cSample 16 was obtained after 24 h of precipitation under aqueous conditions with the same properties of sample 13 and then was kept in a dry and vacuum condition for 2 years as a control sample.