Mineral - Ludlamite
Ludlamite
Chemical Properties
Mineral Class
Phosphates
Toxicity
none
Formula
Fe²⁺₃(PO₄)₂ · 4H₂O
Unit Cell
a=10.54 b=4.65 c=9.32 β=100° Z=2
Physical Properties
Hardness
3.5
Streak
whitegreengreen white
Density
Normal (2-3,5)
Cleavage
Perfect after {001}, indistinct after {100}
Fracture
Tenacity
Brittle
Optical Properties
Color
greencolorless
Birefringence
0.044
Luster
Vitreous
Transparency
translucent,
transparent
Pleochroism
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
P2 1 /c (14)
Habit
leafy, prismatic, tabular
Formation
(1) Secondary, through hydrothermal conversion of primary phosphates (especially Triphylite or Lithiophilite) in granitic pegmatites.
(2) Primary, through direct precipitation from hydrothermal solutions in metallic sulfide deposits under reducing conditions.
Paragenesis
Twinning
Rarity
Rather rare
Synonyms
Ludlamite
Composition
Elements
Mass
P₂O₅
32.95
FeO
49.22
MgO
0.96
H₂O
16.12
New Hampshire (Palache et al. 1952)
Groups and Members
Ludlamite-Group