Crystal Lab › Prototype structures › Trigonal
Sheldrickite (NaCa₃[CO₃]₂F₃[H₂O])
Trigonal · space group P32 (No. 145) · Pearson hP48 · mineral: sheldrickite
Symmetry elements and Wyckoff positions (interactive)
Sheldrickite (NaCa₃[CO₃]₂F₃[H₂O]) in P32
SettingUnit cell
- Lattice constants
- a = 6.726 Å, b = 6.726 Å, c = 15.044 Å; α = 90.00°, β = 90.00°, γ = 120.00°
- Cell volume
- 589.4 ų
- Atoms in the conventional cell
- 48 (C 6, Ca 9, F 9, Na 3, O 21)
- Formula units Z
- 3
- Pearson symbol
- hP48 — hexagonal / trigonal, primitive lattice, 48 atoms per conventional cell
- Symmetry operations
- 3 per cell
Crystallographic sites
| Site | Element | Wyckoff | Multiplicity | x | y | z |
|---|---|---|---|---|---|---|
| C1 | C | 3a | 3 | 0.5670 | 0.3170 | 0.1680 |
| C2 | C | 3a | 3 | 0.4320 | 0.7520 | 0.1690 |
| Ca3 | Ca | 3a | 3 | 0.6161 | 0.9991 | 0.0000 |
| Ca4 | Ca | 3a | 3 | 0.9989 | 0.6284 | 0.0045 |
| Ca5 | Ca | 3a | 3 | 0.3706 | 0.3710 | 0.9957 |
| F6 | F | 3a | 3 | 0.9970 | 0.2660 | 0.0100 |
| F7 | F | 3a | 3 | 0.2710 | 0.0020 | 0.9950 |
| F8 | F | 3a | 3 | 0.7300 | 0.7340 | 0.9800 |
| Na9 | Na | 3a | 3 | 0.0010 | 0.2970 | 0.1650 |
| O10 | O | 3a | 3 | 0.6640 | 0.3480 | 0.0900 |
| O11 | O | 3a | 3 | 0.6680 | 0.3330 | 0.2380 |
| O12 | O | 3a | 3 | 0.3530 | 0.2730 | 0.1670 |
| O13 | O | 3a | 3 | 0.3210 | 0.6540 | 0.9080 |
| O14 | O | 3a | 3 | 0.3360 | 0.6660 | 0.7610 |
| O15 | O | 3a | 3 | 0.6460 | 0.9210 | 0.1650 |
| O16 | O | 3a | 3 | 0.2030 | 0.2020 | 0.8310 |
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 48 atoms drawn above are these sites multiplied by all 3 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
A2B3C3DE7_hP48_145_2a_3a_3a_a_7a-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol hP48, then the space-group number 145, then the Wyckoff letters occupied by each element in turn (C: 3a; C: 3a; Ca: 3a; Ca: 3a; Ca: 3a; F: 3a; F: 3a; F: 3a; Na: 3a; O: 3a; O: 3a; O: 3a; O: 3a; O: 3a; O: 3a; O: 3a). Two structures with the same label are the same arrangement with different cell parameters or coordinates.
Note: Sheldrickite.
Source
Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2B3C3DE7_hP48_145_2a_3a_3a_a_7a-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.