Mineral - Axinite-(Mg)
Axinite-(Mg)
Chemical Properties
Mineral Class
Silicates
Toxicity
none
Formula
Ca₂MgAl₂BSi₄O₁₅OH
Unit Cell
a=7.14 b=9.16 c=8.94 α=92° β=98° γ=78° Z=2
Physical Properties
Hardness
6.5 - 7
Streak
white
Density
Normal (2-3,5)
Cleavage
Good after {100}, poor after {001}, {110} and {011}
Fracture
conchoidal,
uneven
Tenacity
Brittle
Optical Properties
Color
browngraypinkviolet
Birefringence
0.009
Luster
Vitreous
Transparency
translucent,
transparent
Pleochroism
Stark
Geomineralogical Properties
Crystal System
triclinic
Point Group
triclinic-pinacoidal - 1
Space Group
P 1 (2)
Habit
axe-shaped, tabular
Formation
Through metamorphism (mostly contact metamorphism)
Paragenesis
Twinning
Rarity
Very rare
Synonyms
Axinite-(Mg), Axinite
Composition
Elements
Mass
SiO₂
44.00
TiO₂
0.03
B₂O₃
[6.46]
Al₂O₃
17.90
V₂O₃
0.13
MnO
0.40
ZnO
0.06
MgO
6.90
CaO
21.70
K₂O
0.01
H₂O
[1.67]
Tanzania (Jobbins et al. 1975)
Groups and Members
Axinite-Group
Name and first discovery: Named after the ancient Greek word "axina" for "axe", in reference to its crystal form
Chemism:
Synonyms:
Varieties:
Abbreviation: Ax-Mg
Famous sites
(TL) Type locality (analysis) Chemical element distribution, see above
Tanzania
(TL) (Analysis) Merelani Hills, Lelatema Mountains, Manyara, Tanzania
USA
Luning, Fitting Mining District, Mineral County, Nevada, USA
Literature
Jobbins, E. A., Tresham, A. E., & Young, B. R. (1975). Magnesioaxinite, a new mineral found as a blue gemstone from Tanzania. Journalof Gemmology, 14(8), 368-375.