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
SettingUnit 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
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Mg1 | Mg | 8c | 8 | 0.1300 | 0.3300 | 0.3700 |
| Mg2 | Mg | 8c | 8 | 0.1300 | 0.9600 | 0.3700 |
| O3 | O | 8c | 8 | 0.0600 | 0.1400 | 0.2000 |
| O4 | O | 8c | 8 | 0.0600 | 0.5000 | 0.2000 |
| O5 | O | 8c | 8 | 0.0500 | 0.7500 | 0.0500 |
| O6 | O | 8c | 8 | 0.1900 | 0.3500 | 0.0600 |
| O7 | O | 8c | 8 | 0.1900 | 0.0100 | 0.0500 |
| O8 | O | 8c | 8 | 0.2000 | 0.7500 | 0.3000 |
| Si10 | Si | 8c | 8 | 0.2200 | 0.8500 | 0.0400 |
| Si9 | Si | 8c | 8 | 0.0300 | 0.6500 | 0.2900 |
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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