Solid phase
Official name
Synthetic olivine group
Type
Family
ionic solid
Class
mixed salt
Compound type
nesosilicate
Chemical composition
Formula
$(A^{2,3+})_{2-3}(SiO_4^{4-})_{1-2}\ \ \ \ \ $ with $A = Mg^{2+}, Fe^{2+}, Fe^{3+}, Mn^{2+}$ or $Ni^{2+}$
Chemical formula
(Mg,Fe,Mn,Ni)(2-3)(SiO4)(1-2)
Elemental formula
(Mg2+)0-2 (Fe2+)0-2 (Fe3+)0-2 (Ni2+)0-2 (Mn2+)0-2 (Si)1-2 (O-)4-8
Isotope mixture type
terrestrial abundance
13.0
  Formula Name Family Number min-max Mole fraction Isotope mole fraction State Relevance
$Mg^{2+}$ Magnesium(II) cation element 0 - 2 0.15384615384615385 $\pm$ 0.15384615384615385 1 constituent cation main
$Fe^{2+}$ Iron(II) cation element 0 - 2 0.15384615384615385 $\pm$ 0.15384615384615385 1 constituent cation main
$Fe^{3+}$ Iron(III) cation element 0 - 2 0.15384615384615385 $\pm$ 0.15384615384615385 1 constituent cation main
$Ni^{2+}$ Nickel cation element 0 - 2 0.15384615384615385 $\pm$ 0.15384615384615385 1 constituent cation main
$Mn^{2+}$ Manganese(II) cation element 0 - 2 0.15384615384615385 $\pm$ 0.15384615384615385 1 constituent cation main
$(SiO_4)^{4-}$ Silicate anion chemical function 1 - 2 0.23076923076923078 $\pm$ 0.07692307692307693 1 anionic radical main
Chemical bonds
  Bond Number
$\cdot Mg^{2+} \cdot O^{-}-$
$\cdot Fe^{2+} \cdot O^{-}-$
$\cdot (\cdot) Fe^{3+} \cdot O^{-}-$
$\cdot Ni^{2+} \cdot O^{-}-$
$\cdot Mn^{2+} \cdot O^{-}-$
Class
mixed salts (08)
Endmembers
Equivalent mineral
Olivine group
Phase type
crystalline
Crystal system
various
Crystal class
various
Crystal class symbol
various
Crystal spacegroup
various
Comments
mostly orthorhombic system except 1 member. In Mindat the group also includes A=Ca^{2+}
Molar mass
140.69-351.71 $g/mol$
Density
3.21-4.6 $g/cm^3$
State NTP
solid
Refringence type
biaxial
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