Effects of Calcination on the Crystallography and Nonbiogenic Aragonite Formation of Ark Clam Shell under Ambient Condition

Table 1

Several crystal structures of calcium compounds present in ACS after calcination and kept under ambient condition for three months.

Mineral name	Calcite	Aragonite	Vaterite	Portlandite	Lime
Molecular formula	CaCO3	CaCO3	CaCO3	Ca(OH)2	CaO
ICSD code	073446	032100	18127	202231	75785
Crystal system	Trigonal	Orthorhombic	Hexagonal	Trigonal	Cubic
Bravais lattice	Rhombohedral	Primitive	Primitive	Primitive	Face-centered
Space group	()	()	()	()	()
a (nm)	0.4991	0.49610	7.135	0.36041	0.48106
b (nm)	0.4991	0.79670	7.135	0.36041	0.48106
c (nm)	1.7062	0.57410	16.98	0.49620	0.48106