a fluxional bond formed between an ion and a polar molecule. The classic example is where water molecules hydrate a sodium cation. However, the interaction is not restricted to H2O, as many polar organic molecules will form ion-dipole interactions. See fluxional bond.
the ratio (Ip) of charge (z) on an ion to the radius (r) of the ion, IP = z/r.
a description of material with physical properties that are the same regardless of direction of measurement. Cf., anisotropy
discredited term, use kaolin-serpentine group (Bailey, 1980)
a) Petrologic term: rock composed primarily of kaolinite, nacrite, dickite, or halloysite (i.e., minerals of the kaolin group). In most case, the identification of the specific species is unknown. The rock is commonly white, earthy, and soft. b) Mineralogic term: a sub-group name (within the group “serpentine-kaolin”) for those phyllosilicates that are dioctahedral, with 1:1 layers, and with a net layer charge of approximately 0.0. Species of this sub-group include kaolinite, nacrite, dickite and halloysite. Previously, the group name was “serpentine-kaolinite”, and the subgroup name was “kaolinite”, but this scheme created confusion because it was unclear if “kaolinite” was referring to the more general sub-group or the species “kaolinite”. See also Part 2 of the Glossary. Cf., dioctahedral, 1:1 layers
the number of reacting molecules, atoms, or ions in a single-step chemical reaction. For example, a unimolecular reaction may involve radioactive decay of a single atom, or one molecule producing other molecules. A bimolecular reaction involves the collision and reaction between two molecules, atoms or ions to form other products. Cf., Transition State Theory
Nanocomposites are fine-particulate materials that are heterogeneous at the nanoscale level (i.e., less than 10-7 meters). Such materials have structures and properties that are composite-particle-size dependent. The composite-particle size is sufficiently large that it is not considered a chemical (atom) cluster or complex.
single-chain silicate minerals with Si-tetrahedral repeats of 3 (e.g., in wollastonite, CaSiO3), 5 (e.g., in rhodonite, MnSiO3), 7 (e.g., in pyroxmangite, FeSiO3), or 9 (e.g., in ferrosilite III). In contrast, the pyroxene tetrahedral repeat is 2. However, both the pyroxenoids and the pyroxenes have octahedrally coordinated cations connecting to the tetrahedral chains in similar ways. Hydrous pyroxenoids exist also, where Na + H substitute for one of the divalent cations, e.g., pectolite, Ca2NaH(SiO3)3. Wollastonite occurs as a contact metamorphic mineral of siliceous dolomites and is used in the manufacture of tile and in glazes. Rhodonite and pyroxmangite occur in manganese deposits and metamorphosed Mn-rich iron formations. Pectolite, commonly associated with zeolites, forms in cavities in basalts as a secondary mineral formed by hydrothermal activity.
Quartz, SiO2, is comprised of two chains, both spirals of SiO4 tetrahedra parallel to the c axis. In the alpha-quartz structure (low temperature form to 573 oC at 1 bar), these chains are kinked and the structure has trigonal symmetry. In the beta-quartz structure (high temperature form, above 574.3 oC), the chains expand (the tetrahedra are not twisted) and the symmetry is hexagonal with a more open structure than the alpha form. The beta form is non-quenchable and not found under ambient conditions. An intermediate phase between 573 – 574.3 oC is known to exist. Quartz is a common associated phase in clay, but generally forms grains larger than clay particles (about 0.2 – 0.4 micrometers) and therefore quartz particles can be removed by size separation.
Quartzine is a rock term to describe a mixture of a fibrous [0001] variety of microcrystalline (length slow) quartz and moganite. Cf., chalcedony