A discredited term, a mixture of pimelite and Ni-rich serpentine.

An obsolete name.
See brindleyite

The Ni-rich trioctahedral member of the chlorite group.
See chlorite

See astrophyllite group.

See astrophyllite group.

See glaebule.

A solid where the constituent components are randomly packed. Many variations can occur between the two extremes of crystalline vs. non-crystalline. For example, a non-crystalline material, such as many glasses, consists of atoms arranged as groups of tetrahedra or octahedra. However, although such groups have almost the same mutual arrangements, they are displaced without periodicity with respect to each other (i.e., limited order or short-range order). (Quot Guggenheim et al., 2006)
Cf., crystalline

Fe³⁺-bearing and dioctahedral member of the smectite group of minerals. A representative formula is: R0.33Fe3+2(Si3.67Al0.33)O10(OH)2^.nH₂O, where R refers to the exchangeable cation, commonly Na, Ca and Mg, and n is a rational number, not necessarily an integer. The layer charge originates by substitution primarily in the tetrahedral sheet. One of the dominant minerals along mid-ocean ridges.
Cf., smectite

A polymorph of Al(OH)₃ that occurs in bauxites and soils and rarely in dolomitic marls. Nordstrandite is a two-layer, dioctahedral structure of Al octahedra (similar to layers found in gibbsite), but with displacements between the layers. Ideally, adjacent layers are superposed in bayerite, offset in nordstrandite, and reversed in gibbsite, presumably because of strong polarization effects of the OH.
Cf., gibbsite, bayerite

The correlated motion of atoms in a molecule or crystal identified by a specific frequency and with the same phase relations in the vibrational spectrum. The symmetry of the normal mode is related to the symmetry of the molecule or crystal.
Cf., vibrational spectroscopy