General Information:
Chemical Formula:Ca2Mg2Fe+++4(Al,Fe+++)4Si2O20
Composition:(Molecular Weight = 893.97 gm)Calcium 8.97 %
CaMagnesium 5.44 %
MgAluminum 6.04 %
AlIron 37.48 %
FeSilicon 6.28 %
SiOxygen 35.79 %
O Empirical Formula: Ca2Mg2Fe3+6Al2Si2O20
Environment:Occurs in a paralava (pyrometamorhic melt rock) formed from burning coal beds.
IMA Status:Approved IMA
Locality:Druham ranch, 25 km S of Gillette in the Powder River Basin, Wyoming. USA.
Name Origin:Named for John A. Dorr (1922-1986), University of Michigan.
Physical Properties: Cleavage:[001] Distinct, [010] Distinct
Color:brownish black, dark brown, or reddish brown.
Diaphaniety:Subopaque
Habits:Anhedral Grains - Granular minerals without the expression of crystal shapes, Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).,
Hardness:5 - Apatite
Luster:Sub Metallic
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