Lead Phosphoro Chloride
Pb5(PO4)3Cl
Chemical name
Lead Phosphoro Chloride
Mineral name
Pyromorphite
Chemical formula
Pb5(PO4)3Cl
Crystal system
hexagonal
Crystal Class
hexagonal-dipyramidal (6/m)
Space Group
P6_3/m
Unit cell
a [Å]:9.97
b [Å]:9.97
c [Å]:7.32
Molecular weight [g/mol]
1356,36
Formula units
Z=2
Frequent crystal surfaces
{10-10}, {0001}, {10-11}, {20-21}, {11-21}
Twinning
rarely on {11-22}
Mohs hardness
3.5 - 4
Density [g/cm3]
6.7 - 7
Cleavage
imperfect on [10-11]
Fracture / Tenacity
brittle, uneven to conchoidal
Color
dark green to green, yellow, yellow-orange, reddish-orange, yellow-brown to brown, tan, grayish to colorless
Streak
white
Transparency
transparent to translucent
Optical character
uniaxial (-)
Refractive Index
nω=2.058; nε=2.048
Birefringence δ
0.010
Pleochroism δ
weak