Vermiculite [Mg₂Si₂O₅(H₂O)_{1.86}(OH)Si₂]

Unit cell

Lattice constants

a = 5.349 Å, b = 9.255 Å, c = 28.890 Å; α = 90.00°, β = 97.12°, γ = 90.00°

Cell volume

1419.2 ų

Atoms in the conventional cell

104 (Mg 16, H 24, O 48, Si 16)

Formula units Z

8

Pearson symbol

mC104 — monoclinic, base-centred lattice, 104 atoms per conventional cell

Symmetry operations

8 per cell

Crystallographic sites

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 104 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

A3B2C5DE2_mC104_15_3f_a3e_5f_f_2f-001: the stoichiometry comes first (A, B, C… are the elements in alphabetical order of their site labels), then the Pearson symbol mC104, then the space-group number 15, then the Wyckoff letters occupied by each element in turn (Mg: 4a; Mg: 4e; Mg: 4e; Mg: 4e; H: 8f; H: 8f; H: 8f; O: 8f; O: 8f; O: 8f; O: 8f; O: 8f; O: 8f; Si: 8f; Si: 8f). Two structures with the same label are the same arrangement with different cell parameters or coordinates.

Note: Vermiculite.

Source

Coordinates and cell from the AFLOW Encyclopedia of Crystallographic Prototypes, entry A3B2C5DE2_mC104_15_3f_a3e_5f_f_2f-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.