Crystal Lab › Prototype structures › Trigonal
Steklite [KAl(SO₄)₂, H3₂]
Trigonal · space group P321 (No. 150) · Pearson hP12 · Strukturbericht H32 · mineral: steklite
Symmetry elements and Wyckoff positions (interactive)
Steklite [KAl(SO₄)₂, H3₂] in P321
SettingUnit cell
- Lattice constants
- a = 4.700 Å, b = 4.700 Å, c = 7.960 Å; α = 90.00°, β = 90.00°, γ = 120.00°
- Cell volume
- 152.3 ų
- Atoms in the conventional cell
- 12 (Al 1, K 1, O 8, S 2)
- Formula units Z
- 1
- Pearson symbol
- hP12 — hexagonal / trigonal, primitive lattice, 12 atoms per conventional cell
- Symmetry operations
- 6 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| Al1 | Al | 1a | 1 | 0.0000 | 0.0000 | 0.0000 |
| K2 | K | 1b | 1 | 0.0000 | 0.0000 | 0.5000 |
| O3 | O | 2d | 2 | 0.3333 | 0.6667 | 0.5160 |
| S5 | S | 2d | 2 | 0.3333 | 0.6667 | 0.7220 |
| O4 | O | 6g | 6 | 0.3280 | 0.3440 | 0.8170 |
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 12 atoms drawn above are these sites multiplied by all 6 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
ABC8D2_hP12_150_a_b_dg_d-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol hP12, then the space-group number 150, then the Wyckoff letters occupied by each element in turn (Al: 1a; K: 1b; O: 2d; S: 2d; O: 6g). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Other compounds with this structure
NH₄(Al, Fe)(SO₄)₂ (godovikovite), KCr(SO₄)₂, RbCr(SO₄)₂ <!--beginning with an
Note: H3₂, Steklite.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry ABC8D2_hP12_150_a_b_dg_d-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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