Mineral phase
IMA name
Aragonite
Secondary names
Calcium carbonate; Ca carbonate
IMA Code
Arg
Type
Class
non-silicate mineral
Compound type
carbonate
Comments
Equivalent Space Group: Pmcn (62)
Chemical composition
Formula
$CaCO_3$
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
$Ca^{2+}$ Calcium cation element 1 constituent cation main
$(CO_3)^{2-}$ Carbonate anion chemical function 1 anionic radical main
Chemical functions
  Function Number
$(CO_3)^{2-}$ 1
Chemical bonds
  Bond Number
$\cdot Ca^{2+} \cdot O^{-}-$ 2
$\dddot - \dddot - C \dddot - O^{-2/3}$ 3
Oxides
Formula $CaO$ $CO_{2}$
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 $g/cm^3$
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 $10^7$ to $10^8$ yearsat room temperature
Refringence type
biaxial
Refringence sign
negative
Birefringence
0.156
Refraction index $n_{\alpha}$
1.529 - 1.53
Refraction index $n_{\beta}$
1.68 - 1.682
Refraction index $n_{\gamma}$
1.685-1.686
Pure color
colorless
Color
colorless, white, grey, yellow
Diaphaneity
transparent to translucent
Luster
vitreous
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