An obsolete term for nontronite.
An obsolete term for nontronite.
A Monte Carlo molecular simulation that is based on the grand canonical thermodynamic ensemble, an ensemble (e.g., a system of particles) in statistical mechanics that describes the possible states of the particles in equilibrium. The model system properties of chemical potential, volume, and temperature are held constant, but the number of particles in the system (e.g., interlayer water molecules) is allowed to vary as equilibrium is achieved. In this context, equilibrium implies both potential energy and system density (number of particles). Monte Carlo moves are accepted based on the energy change of the move according to a Boltzmann probability (so that some moves resulting in higher energy are accepted).
Cf., force field, molecular dynamics, Monte Carlo molecular simulation
See garnet.
A green body is an unfired clay-based object, e.g., made from mixtures of milled clay, quartz, feldspar, and appropriate amounts of water, and formed by molding, pressing, or by a potter’s wheel. The green body is fired in kilns to obtain a ceramic object.
Syn., greenware;
Cf., ceramic, pottery
a) In clayware manufacture, the ability of an unfired, molded clay body to resist mechanical deformation.
b) In metal casting, a measure of the ability of a bentonite-bound sand mold to resist deformation (also called “green sand strength”).
A modulated 1:1 layer silicate based on the serpentine structure, with an approximate ideal composition of Fe2+3Si2O5(OH)4. Mn, Mg, and Al can substitute for Fe. There is an apparent excess of Si and an apparent deficiency in octahedral composition on the basis of 7 oxygen atoms. Earlier literature erroneously described greenalite as an iron serpentine, similar to the structure of lizardite. The 1T polytype (space group P31m) is dominant and the 1M polytype (space group Cc) is often intergrown. Greenalite is an “island” structure where Si-rich tetrahedra of a given layer have apical oxygen atoms coordinate to one octahedral sheet and others to the adjacent sheet (Guggenheim and Eggleton, 1998). The islands are saucer-shaped with some islands inverted, and the islands are domed. Island diameters depend on composition with larger-diameter islands having smaller average octahedral cation sizes (4 tetrahedral-ring diameters in greenalite, 3 rings in the Mn analogue, caryopilite). Island domains are randomly displaced within layers. Greenalite is commonly found in Precambrian iron formations.
Cf., caryopilite
A poorly described material, possibly chlorite, from Griffith Park, Los Angeles, California, USA.
A qualitative term in the clay-mining industry that refers to small, hard accessory minerals occurring in the bulk clay deposit, such as quartz, feldspar, rutile, ilmenite, and apatite, which imparts an undesirable “abrasive” character to the bulk clay.
Water existing underground in voids or pore spaces in rock or sediment.
Phyllosilicates are classified on the basis of characteristics involving planar structures, non-planar structures and regular interstratifications (e.g., Guggenheim et al., 2006). For planar structures and regular interstratifications, the layer type (e.g., 1:1, 2:1) is further divided by interlayer material present that is required to offset the net negative charge on the layer, and each division is given a group name. In addition, each group has a generally characteristic spacing [based on the d(001)] perpendicular to the stacking direction, i.e., csinβ. The group names (x ~ layer charge per formula unit) for the planar structures (interstratifications are not given here) are: serpentine-kaolin (x ~ 0, csinβ ~ 7.1-7.3 Å), talc-pyrophyllite (x ~ 0, csinβ ~ 9.1-9.4 Å), smectite (x ~ -0.2 to -0.6, csinβ ~ 14.4-15.6 Å), vermiculite (x ~ -0.6 to -0.9, csinβ ~ 14.4-15.6 Å), true mica (x ~ -1.0, csinβ ~ 9.6-10.1 Å), brittle mica (x ~ -2.0, csinβ ~ 9.6- 10.1 Å), interlayer-deficient mica (x ~ -0.6 to -0.85, csinβ ~ 9.6-10.1 Å), and chlorite (x ~ variable, csinβ ~ 14.0-14.4 Å). Groups are further divided into subgroups (e.g., serpentine, kaolin, talc, pyrophyllite, trioctahedral smectite, dioctahedral smectite, etc.) by mineral species based on the octahedral character (i.e., dioctahedral, trioctahedral) and subgroups are divided based on chemical composition to mineral species. Bailey (1980) designated the trioctahedral smectite subgroup as saponite and the dioctahedral smectite subgroup as montmorillonite.