Mineral phase
IMA name
Aragonite
Secondary names
Calcium carbonate; Ca carbonate
IMA Code
Arg
Class
non-silicate mineral
Compound type
carbonate
Comments
Equivalent Space Group: Pmcn (62)
Formula
CaCO3
Chemical formula
CaCO3
Elemental formula
(Ca2+) C O (O-)2
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
Ca2+ Calcium cation element 1 constituent cation main
(CO3)2 Carbonate anion chemical function 1 anionic radical main
Chemical functions
  Function Number
(CO3)2 1
Chemical bonds
  Bond Number
Ca2+O 2
CO2/3 3
Oxides
Formula CaO CO2
Mass fraction (%) 56.03 43.97

Strunz

Class
carbonates - nitrates (05)
Division
carbonates without additional anions, without H2O (05.A)
Family
Alkali-earth (and other M2+) carbonates (05.AB)
Code
05.AB.15

Dana

Major class
carbonates, nitrates, borates (V)
Class
anhydrous carbonates (14)
Type
with simple formula A+CO3 (14.01)
Group
Aragonite group (Orthorhombic: Pmcn) (14.01.03)
Code
14.01.03.01
Phase type
crystalline
Crystal system
orthorhombic
Crystal class
dipyramidal
Crystal class symbol
mmm (D2h)
Crystal spacegroup
Pnma
Molar mass
100.09 g/mol
Density
2.93 g/cm3
State NTP
metastable solid - other solid
Phase transitions
Phase transition type Other phases Temperature - Pressure
solid-solid Calcite below 3kb at room temperature, but very slow
Phase transitions comments
tends to alter to calcite on scales of 107 to 108 yearsat room temperature
Refringence type
biaxial
Refringence sign
negative
Birefringence
0.156
Refraction index nα
1.529 - 1.53
Refraction index nβ
1.68 - 1.682
Refraction index nγ
1.685-1.686
Pure color
colorless
Color
colorless, white, grey, yellow
Diaphaneity
transparent to translucent
Luster
vitreous