monoclinic Chromates
Crocoite
PbCrO4
Crystal Structure
#! Species: Crocoite
#! System: Monoclinic (2/m)
#! Habit: Elongated prismatic with adamantine lustre
monoclinic[2/m]:{110}@1.0 + {100}@0.7 + {001}@0.5 | elongate(c:3.0)
monoclinic
2/m
{110} {100} {001}
Quick Facts
Hardness
2.5
Specific Gravity
5.97
Refractive Index
2.31
Optical Character
Biaxial +
Physical Properties
Crystal Systemmonoclinic
Hardness (Mohs)2.5
Specific Gravity5.97
CleavageDistinct {110}
FractureConchoidal to uneven
LustreAdamantine to vitreous
Optical Properties
Refractive Index2.31
Birefringence0.37
Optical CharacterBiaxial +
PleochroismWeak (red to orange-red)
Colours
Orange-redRedHyacinth redYellow-orange
Localities
Tasmania (Australia - Dundas, Red Lead Mine)Russia (Urals - historic type locality)BrazilPhilippinesZimbabwe
Crystal Forms
prism (elongated)pinacoid
Notes
RI over refractometer limit; extremely high birefringence; contains lead - wash hands after handling
Related Minerals
Other minerals in the monoclinic system
Actinolite (Prismatic)
Ca2(Mg,Fe)5Si8O22(OH)2
Augite (Prismatic)
(Ca,Na)(Mg,Fe,Al)(Si,Al)2O6
Azurite
Cu3(CO3)2(OH)2
Chrome Diopside
CaMg1-xCrxSi2O6
Diopside
CaMgSi2O6
Dyed Howlite (Turquoise Simulant) (Dyed Howlite (Blue))
Ca2B5SiO9(OH)5 (calcium borosilicate hydroxide; dyed blue to simulate turquoise)