Mineral - Arrojadite-(KFe)
Arrojadite-(KFe)
Chemical Properties
Mineral Class
Phosphates
Toxicity
none
Formula
(KNa)(Fe²⁺ □)Ca(Na₂ □)Fe²⁺₁₃Al(PO₄)₁₁(PO₃OH)(OH)₂
Unit Cell
a=16.45 b=10.00 c=24.69 β=106° Z=4
Physical Properties
Hardness
5
Streak
white
Density
Normal (2-3,5)
Cleavage
Good after {100}, distinct after {010}
Fracture
uneven
Tenacity
Brittle
Optical Properties
Color
brownyellowgreen
Birefringence
0.011
Luster
Vitreous
Transparency
translucent,
transparent
Pleochroism
X: Farblos
Y: Farblos-Grün
Z: Gelb-Grün
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-domatic - m
Space Group
Cc (9)
Habit
Rhombohedron, Rhombohedral, tabular
Formation
Magmatic, in granitic pegmatites (approx. 800°C)
Paragenesis
Twinning
Rarity
Very rare
Synonyms
Arrojadite-(KFe), Arrojadite
Composition
Elements
Mass
P₂O₅
40.70
Al₂O₃
2.42
FeO
28.48
MnO
14.56
ZnO
0.40
MgO
1.37
Li₂O
0.26
Na₂O
6.16
K₂O
1.71
CaO
2.51
SrO
0.06
BaO
0.12
PbO
0.20
F
1.07
H₂O
0.94
South Dakota (Chopin et al. 2006)
Groups and Members
Arrojadite-Group
Name and first discovery : Named after the Brazilian geologist Miguel Arrojado Ribeiro Lisboa (1872-1932). First described in 1925 from Brazil.
Chemistry :
Synonyms : Headdenite
Varieties :
Abbreviation : Ajd-KFe
literature
Chopin, C., Oberti, R., & Cámara, F. (2006). The arrojadite enigma: II. Compositional space, new members, and nomenclature of the group. American Mineralogist , 91 (8-9), 1260-1270.