Gadolinite
Refractive Index nx
1.770 - 1.780
Refractive Index ny
1.780 -
Refractive Index nz
-
Birefringence
0.010 - 0.040
Density
4.00 - 4.65
Polariscope
2 positive, iso
Colours:
brown, green, black
Transparency:
Translucent, Opaque
Remarks:
Usually metamict and amorphous
Hardness:
6,5 - 7
Formula:
Be2Fe(Ce,La,Nd,Y)2Si2O10
System:
Monoclinic
Rare?
5