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Crystal Lab › Prototype structures › Orthorhombic

Enstatite (MgSiO₃, S4₃)

Orthorhombic · space group Pbca (No. 61) · Pearson oP80 · Strukturbericht S43 · mineral: enstatite

Symmetry elements and Wyckoff positions (interactive)

Enstatite (MgSiO₃, S4₃) in Pbca

Setting
Loading the group…
x = 0.10, y = 0.17, z = 0.08

Unit cell

Lattice constants
a = 18.200 Å, b = 8.860 Å, c = 5.200 Å; α = 90.00°, β = 90.00°, γ = 90.00°
Cell volume
838.5 ų
Atoms in the conventional cell
80 (Mg 16, O 48, Si 16)
Formula units Z
16
Pearson symbol
oP80 — orthorhombic, primitive lattice, 80 atoms per conventional cell
Symmetry operations
8 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Mg1Mg8c80.13000.33000.3700
Mg2Mg8c80.13000.96000.3700
O3O8c80.06000.14000.2000
O4O8c80.06000.50000.2000
O5O8c80.05000.75000.0500
O6O8c80.19000.35000.0600
O7O8c80.19000.01000.0500
O8O8c80.20000.75000.3000
Si10Si8c80.22000.85000.0400
Si9Si8c80.03000.65000.2900

The multiplicity and the Wyckoff letter say how many copies of the site the group makes in one cell and on which kind of symmetry element the site sits; the 80 atoms drawn above are these sites multiplied by all 8 operations. Press Wyckoff under Colour to see the sites, and tick a symmetry element on the left to see which atoms lie on it.

How to read the label

AB3C_oP80_61_2c_6c_2c-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oP80, then the space-group number 61, then the Wyckoff letters occupied by each element in turn (Mg: 8c; Mg: 8c; O: 8c; O: 8c; O: 8c; O: 8c; O: 8c; O: 8c; Si: 8c; Si: 8c). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Other compounds with this structure

FeSiO₃ (ferrosilite), CoGeO₃, CoSiO₃ (Co-pyroxene), MgGeO₃ <!--beginning with an

Note: S4₃, Enstatite.

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry AB3C_oP80_61_2c_6c_2c-001 (M. J. Mehl et al., Comput. Mater. Sci. 136, S1 (2017); D. Hicks et al., ibid. 161, S1 (2019) and 199, 110450 (2021); S. Eckert et al., ibid. 240, 112988 (2024)). Symmetry elements, Wyckoff assignment and the diagram are computed on this page from the group operations.

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