-    CUMMINGTONITE     -    Mg7Si8O22(OH)2

 

Crystal Structure 


Because of the translational symmetry all the calculations are performed in the primitive unit cell and not in the conventional unit cell. The following information regarding the structure is given with respect to this primitive unit cell, which sometimes can take an unintuitive shape.

Symmetry (experimental): 

Space group:  12  C2/m 
Lattice parameters (Å):  9.5015  18.1289  5.3089 
Angles (°):  90  102.090  90 

Symmetry (theoretical): 

Space group:  12  C2/m 
Lattice parameters (Å):  0.5292  0.5292  0.5292 
Angles (°):  84.26  95.73  55.13 

Cell contents: 

Number of atoms:  41 
Number of atom types: 
Chemical composition: 

Atomic positions (theoretical):

Mg:  0.0855  0.0855  0.5000 
Mg:  0.1753  0.1753  0.0000 
Mg:  0.0000  0.0000  0.0000 
Mg:  0.2520  0.2520  0.5000 
Si:  0.3754  0.7938  0.2765 
Si:  0.4705  0.8713  0.7817 
O:  0.2003  0.9717  0.2109 
O:  0.2941  0.0507  0.7161 
O:  0.1153  0.8847  0.7094 
O:  0.6281  0.8696  0.7649 
O:  0.4892  0.7805  0.0705 
O:  0.4730  0.7639  0.5644 
O:  0.3497  0.6503  0.2652 
H:  0.2221  0.7779  0.7516 
Si:  0.7938  0.3754  0.7235 
Si:  0.8713  0.4705  0.2183 
O:  0.9717  0.2003  0.7891 
O:  0.0507  0.2941  0.2839 
O:  0.8847  0.1153  0.2906 
O:  0.8696  0.6281  0.2351 
O:  0.7805  0.4892  0.9295 
O:  0.7639  0.4730  0.4356 
O:  0.6503  0.3497  0.7348 
H:  0.7779  0.2221  0.2484 
Mg:  0.9145  0.9145  0.5000 
Mg:  0.8247  0.8247  0.0000 
Mg:  0.7480  0.7480  0.5000 
Si:  0.6246  0.2062  0.7235 
Si:  0.5295  0.1287  0.2183 
O:  0.7997  0.0283  0.7891 
O:  0.7059  0.9493  0.2839 
O:  0.3719  0.1304  0.2351 
O:  0.5108  0.2195  0.9295 
O:  0.5270  0.2361  0.4356 
Si:  0.2062  0.6246  0.2765 
Si:  0.1287  0.5295  0.7817 
O:  0.0283  0.7997  0.2109 
O:  0.9493  0.7059  0.7161 
O:  0.1304  0.3719  0.7649 
O:  0.2195  0.5108  0.0705 
O:  0.2361  0.5270  0.5644 
Atom type 

We have listed here the reduced coordinates of all the atoms in the primitive unit cell.
It is enough to know only the position of the atoms from the assymetrical unit cell and then use the symmetry to build the whole crystal structure.

Visualization of the crystal structure: 

Size:

Nx:  Ny:  Nz: 
You can define the size of the supercell to be displayed in the jmol panel as integer translations along the three crys­tallo­gra­phic axis.
Please note that the structure is represented using the pri­mi­tive cell, and not the conventional one.