A poorly crystallized (i.e., lacks long-range atomic order) hydrous aluminosilicate of approximate composition of (OH)₃Al₂O₃SiOH, with a natural-samples range of Al₂(OH)₃(SiO₂)_1.0-1.2(H₂O)_2.3-3.0. The Si/Al ratio is near 0.5. The structure consists of nanotubes, often occurring in closest packing arrangements about 2nm in diameter and to several micrometers in length, typically forming bundles 10 to 30 nm across. The morphology makes imogolite potentially useful in industry for contaminant sorption, gas storage, as an oxidation catalyst, and as an electron emitter. Imogolite has a gibbsite-like structure with Si tetrahedra spanning the vacant octahedral sites, and because of the mismatch in size between the vacant site and the tetrahedron, the gibbsite-like sheet rolls. Imogolite forms from weathered volcanic ash, but may also occur in podzolized soils and in pumice. 
Cf., allophane

Incongruent dissolution is where the release of constituents from the dissolving phase into the solution does not reflect the stoichiometry of the original phase.
Cf., congruent melting, congruent dissolution, incongruent melting

A reaction where the solid phase reacts to form a mixture of liquid plus crystals, with neither having the composition of the original solid.
Cf., congruent melting, incongruent dissolution

An obsolete, local term for a halloysite from Lawrence County, Indiana, in beds to 3 meters thick; may have been used as a rock name for these beds.

Hardening of a rock or sediments by the effects of temperature, pressure, cementation, etc.

a) the phenomenon by which minerals are formed in another environment in space or time from that where they are now found.

b) The term is also used when some element of a pre-existing mineral structure is inherited by another mineral via the phenomenon of transformation.
See also neoformation, transformation

Inner sphere complexes are ions, which adsorb in the inner Helmholtz plane. There is spectroscopic evidence that these ions come so close to the surface that, e.g., water molecules from a hydration shell have to be removed from the contact plane. Since adsorption of ions on an increasingly charged surface requires energy from bonding, one speaks of specific adsorption.

A modulated 1:1 layer silicate with a continuous edge-sharing, Mn-rich octahedral sheet, and an interstratified continuous tetrahedral sheet consisting of 8-, 6-, 5-, and 4-member tetrahedral rings that cross link the octahedral sheet (Krüger et al., 2014). The chemical composition is ideally Mn₃₃(Si₂O₅)₁₄(OH)₃₈. The type locality, near Tyrol, Austria, is located between a serpentinite and chert body, and it appears that the Mn-rich sediments were deposited in deep water and metamorphosed.
Cf., bementite, pyrosmalite, varennesite.

Materials that are poor conductors of electricity.
Syn., dielectric

A thermodynamic property that is independent of the amount of a substance, such as the property of heat capacity.
Cf., extensive property