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Crystal Lab › Prototype structures › Trigonal

Brucite [Mg(OH)₂]

Trigonal · space group P-3m1 (No. 164) · Pearson hP5 · mineral: brucite

Symmetry elements and Wyckoff positions (interactive)

Brucite [Mg(OH)₂] in P-3m1

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

Unit cell

Lattice constants
a = 3.150 Å, b = 3.150 Å, c = 4.770 Å; α = 90.00°, β = 90.00°, γ = 120.00°
Cell volume
41.0 ų
Atoms in the conventional cell
5 (Mg 1, H 2, O 2)
Formula units Z
1
Pearson symbol
hP5 — hexagonal / trigonal, primitive lattice, 5 atoms per conventional cell
Symmetry operations
12 per cell

Crystallographic sites

SiteElementWyckoffMultiplicityxyz
Mg2Mg1a10.00000.00000.0000
H1H2d20.33330.66670.4130
O3O2d20.33330.66670.2203

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 5 atoms drawn above are these sites multiplied by all 12 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

A2BC2_hP5_164_d_a_d-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol hP5, then the space-group number 164, then the Wyckoff letters occupied by each element in turn (Mg: 1a; H: 2d; O: 2d). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Other compounds with this structure

Ca(OH)₂ (Portlandite), Fe(OH)₂, Mn(OH)₂ (Pyrochroite), Ni(OH)₂ (Theophrastite), β-Co(OH)₂ <!--beginning with an

Note: Brucite.

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A2BC2_hP5_164_d_a_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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