General Information:
Chemical Formula:Na2Ca(Mg,Fe++)4Fe+++Si7AlO22(OH)2
Composition:(Molecular Weight = 824.40 gm)Sodium 5.58 %
NaCalcium 4.86 %
CaMagnesium 8.84 %
MgAluminum 3.27 %
AlIron 6.77 %
FeSilicon 23.85 %
SiHydrogen 0.24 %
H Oxygen 46.58 %
O Empirical Formula: Na2CaMg3Fe2+Si7AlO22(OH)2
Environment:Found in basic alkaline igneous rocks.
IMA Status:Approved IMA 1997
Name Origin:Named for its composition and from the Greek for "carrying down", in allusion to its volcanic origin.
Physical Properties: Cleavage:[110] Good, [010] Parting
Color:dark green.
Density:3.2 - 3.5, Average = 3.35
Diaphaniety:Translucent
Hardness:5-6 - Between Apatite and Orthoclase
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