Mineral phase
IMA name
Calcium Amphibole Subgroup
Type
Class
silicate mineral
Compound type
inosilicate
Chemical composition
Formula
$Na_{0-1}Ca_2((Mg^{2+},Fe^{2+})_{5-m}(Al,Fe^{3+},Ti)_m)(Si_{8-(n+m)}Al_{(n+m)})O_{22}(OH,F)_2$ \ \ \ \ \ with m = 0, 1, 2
Chemical formula
(Na)0-1Ca2(Mg,Fe,Al,Ti)5(Si,Al)8O22(OH,F)2
Elemental formula
(Ca)2-3 (Na+)0-1 (Mg2+)0-5 (Fe2+)0-5 (Al3+)0-5 (Fe3+)0-2 (Ti4+)0-1 (Si)5-8 O22 (F)0-2 (H)0-2 (O-)0-2
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Ca$ Calcium element 2 - 3 constituent element main
$Na^+$ Sodium cation element 0 - 1 constituent element main
$Mg^{2+}$ Magnesium(II) cation element 0 - 5 constituent element main
$Fe^{2+}$ Iron(II) cation element 0 - 5 constituent element main
$Al^{3+}$ Aluminium(III) cation element 0 - 5 constituent element main
$Fe^{3+}$ Iron(III) cation element 0 - 2 constituent element main
$Ti^{4+}$ Titanium(IV) cation element 0 - 1 constituent element main
$Si$ Silicon element 5 - 8 constituent element main
$O$ Oxygen element 22 constituent element main
$F$ Fluorine element 0 - 2 constituent element main
$(OH)^-$ Hydroxide anion chemical function 0 - 2 anionic radical main
Composition comments
with Mg+Fe+Mn+Li < 1.5, and Ca+Na ≥ 1.00 and Na < 0.50 -- K+, (and Ba2+, Sr2+, Ca2+, Li+) can replace Na+; Na+, Mg2+, Fe2+, Mn2+, Li+ (and Sr2+, Ba2+, Mn2+, Fe2+, Co2+, Ni2+, Zn2+, Mg2+, Pb2+, Cu, Zr, Mn3+, Cr3+, V, Fe3+) can partly replace Ca2+; Mn2+, Li+, Zn2+, Ni2+, Co2+, Fe3+, V, Cr3+, Mn3+, Zr can partly replace (Mg,Fe,Al,Ti); Ti can partly replace (Si,Al); Cl, O can partly replace (OH,F)
Chemical functions
  Function Number
$(OH)^-$
Chemical bonds
  Bond Number
$O^--H$ 1
Oxides
Formula $CaO$ $Na_{2}O$ $MgO$ $FeO$ $Fe_{2}O_{3}$ $Al_{2}O_{3}$ $TiO_{2}$ $SiO_{2}$ $F$ $H_{2}O$
Mass fraction (%)

Strunz

Class
silicates (09)
Division
inosilicate (09.D)
Family
with 2-periodic double chains, Si4O11; amphibole family (09.DE)

Dana

Major class
silicates (VIII)
Class
inosilicate double-width unbranched chains, w=2 (66)
Type
with P=2 amphibole configuration (66.01)
Group
group 2, the calcic amphiboles (66.01.03a)
Phase type
crystalline
Crystal system
monoclinic
Crystal class
prismatic
Crystal class symbol
2/m (C2h)
Crystal spacegroup
C2/m
State NTP
solid
Refringence type
biaxial
Links