Ca2(Mg,Fe,Al)5(Al,Si)8O22(OH)2Monoclinic
Hornblende
Ca2(Mg,Fe,Al)5(Al,Si)8O22(OH)2
SilicatesChemical FormulaCa2(Mg,Fe,Al)5(Al,Si)8O22(OH)2
Crystal SystemMonoclinic
Mohs Hardness5.5
Specific Gravity3.15
ColorBlack to dark green
LusterVitreous to dull
StreakBrownish gray
CleavageTwo directions at 56/124
FractureUneven
Occurrence
Common amphibole found in many igneous and metamorphic rocks.