Table 2. Percentage of CaCO₃ Polymorphs, Organic Material Content, and Crystallite Size of gCC, Oyster Shell, Scallop Shell, and Clam Shell Powder after Different Times of Ball Milling Using Cyclohexane As Dispersing Agent and 10 wt % Na₂CO₃ as Additive for Amorphization with the Instrumental Error Reported.

Sample	Mill time (hour)	Calcite (wt %)	Aragonite (wt %)a	ACC (wt %)b	O.M.b (wt %)	d(104)/d(111)c (nm)
geo CaCO3	1	70 ± 2	–	30 ± 2	0.1 ± 0.1	11.1 ± 0.3
	6	64 ± 2	–	36 ± 2	0.1 ± 0.1	8.3 ± 0.1
	24	58 ± 2	–	42 ± 2	0.1 ± 0.1	7.5 ± 0.1
oyster shell	1	79 ± 2	5 ± 2	16 ± 2	0.5 ± 0.1	14.2 ± 0.5
	6	42 ± 2	18 ± 2	40 ± 2	0.5 ± 0.1	6.7 ± 0.2/12.0 ± 1.2
	24	45 ± 2	26 ± 2	28 ± 2	0.5 ± 0.1	7.1 ± 0.2/13.7 ± 0.9
scallop shell	1	65 ± 2	10 ± 2	25 ± 2	0.4 ± 0.1	14.3 ± 0.6/15.0 ± 1.0
	6	38 ± 2	16 ± 2	46 ± 2	0.5 ± 0.1	8.9 ± 0.3/12.2 ± 0.8
	24	27 ± 2	68 ± 2	5 ± 2	0.6 ± 0.1	29.0 ± 3.0/40.0 ± 3.0
clam shell	1	11 ± 2	68 ± 2	21 ± 2	0.7 ± 0.1	11.5 ± 0.7/18.6 ± 0.3
	6	29 ± 2	31 ± 2	39 ± 2	0.8 ± 0.1	6.7 ± 0.1/12.0 ± 0.3
	24	72 ± 2	23 ± 2	4 ± 2	0.7 ± 0.1	24.0 ± 1.0/52.0 ± 22.0

^aPercentage of crystalline phases.

^bPercentage of ACC in the powder material determined by analyzing the X-ray diffraction profile. O.M. indicates intraskeletal organic matter and water.

^cThe crystallite size was calculated along the (104) and the (111) zone axis for calcite and aragonite, respectively.