Crystal Lab › Prototype structures › Orthorhombic
Guyanaite (β-CrOOH)
Orthorhombic · space group Pmn21 (No. 31) · Pearson oP8 · mineral: guyanaite
Symmetry elements and Wyckoff positions (interactive)
Guyanaite (β-CrOOH) in Pmn21
SettingUnit cell
- Lattice constants
- a = 2.957 Å, b = 4.297 Å, c = 4.862 Å; α = 90.00°, β = 90.00°, γ = 90.00°
- Cell volume
- 61.8 ų
- Atoms in the conventional cell
- 8 (Cr 2, H 2, O 4)
- Formula units Z
- 2
- Pearson symbol
- oP8 — orthorhombic, primitive lattice, 8 atoms per conventional cell
- Symmetry operations
- 4 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Cr1 | Cr | 2a | 2 | 0.0000 | 0.2560 | 0.0000 |
| H2 | H | 2a | 2 | 0.0000 | 0.2110 | 0.4725 |
| O3 | O | 2a | 2 | 0.0000 | 0.4690 | 0.6360 |
| O4 | O | 2a | 2 | 0.0000 | 0.0030 | 0.3330 |
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 8 atoms drawn above are these sites multiplied by all 4 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
ABC2_oP8_31_a_a_2a-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol oP8, then the space-group number 31, then the Wyckoff letters occupied by each element in turn (Cr: 2a; H: 2a; O: 2a; O: 2a). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
InOOH <!--beginning with an
Note: Guyanaite, \beta-CrOOH.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry ABC2_oP8_31_a_a_2a-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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