Mineral phase
IMA name
Alstonite
Secondary names
Barium calcium carbonate; Ba-Ca carbonate
IMA Code
Asn
Type
Class
non-silicate mineral
Compound type
carbonate
Chemical composition
Formula
$BaCa(CO_3)_2$
Chemical formula
BaCa(CO3)2
Elemental formula
(Ba2+) (Ca2+) C2 O2 (O-)4
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Ba^{2+}$ Barium cation element 1 constituent cation main
$Ca^{2+}$ Calcium cation element 1 constituent cation main
$(CO_3)^{2-}$ Carbonate anion chemical function 2 anionic radical main
Chemical functions
  Function Number
$(CO_3)^{2-}$ 2
Chemical bonds
  Bond Number
$\cdot Ba^{2+} \cdot O^{-}-$ 2
$\cdot Ca^{2+} \cdot O^{-}-$ 2
$\dddot - \dddot - C \dddot - O^{-2/3}$ 3
Oxides
Formula $BaO$ $CaO$ $CO_{2}$
Mass fraction (%) 51.55 18.85 29.59

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.35

Dana

Major class
carbonates, nitrates, borates (V)
Class
anhydrous carbonates (14)
Type
with compound formula A+B++(CO3)2 (14.02)
Group
-Alstonite- group (14.02.05)
Code
14.02.05.01
Phase type
crystalline
Crystal system
triclinic
Crystal class
pedial
Crystal class symbol
1 (C1)
Crystal spacegroup
P1
Comments
P1 (pedial, 1 (C1)) or P-1 (pinacoidal, -1 (Ci)) group
Molar mass
297.42 $g/mol$
Density
3.69 - 3.71 $g/cm^3$
State NTP
solid
Refringence type
biaxial
Refringence sign
negative
Birefringence
0.1460
Refraction index $n_{\alpha}$
1.526
Refraction index $n_{\beta}$
1.671
Refraction index $n_{\gamma}$
1.672
Dispersion V
r > v weak
Pure color
colorless
Color
colorless, gray, white, pink
Diaphaneity
transparent to translucent
Luster
vitreous
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