An obsolete term for chromian muscovite, chromian phengite.

An obsolete term for chromian muscovite.

A dioctahedral member of the true mica group. The ideal end-member formula is KCr₂□AlSi₃O₁₀(OH,F)₂, where □ = vacancy. Chromphyllite, like muscovite, occurs as the 2M₁ polytype in C2/c symmetry, and the Cr forms a solid solution series with Al in muscovite. Chromphyllite is known from the Lake Baikal region, Russia, Outokumpu, Finland, and elsewhere, and is believed to occur in association with metasomatism.
Cf., muscovite

An obsolete term for clintonite.

A member of the serpentine group with textures showing packets of cylinders, scrolls, and tubes, as well as helical or spiral fibers. Chrysotile, ideally Mg₃Si₂O₅(OH)₄, crystallizes in monoclinic symmetry (clinochrysotile) with the fiber axis parallel to X and orthorhombic symmetry with the fiber axis along X (orthochrysotile) or Y (parachrysotile). Polytype stacking for clinochrysotile is either 2M_c1 or 1M_c1, where the number of layers (e.g., 1 or 2) precedes M = monoclinic, subscript c = cylindrical, and subscript 1 is used to distinguish the form from another cylindrical polytype that would otherwise have the same symbol. The orthochrysotile polytype is 2O_c1. Cylindrical structures do not have consistent hydrogen bonding between layers that would be observed in an ideal platy structure, and thus do not conform to the standard polytypes. Fiber dimensions are variable with inner diameters near 70-80 Å and outer diameters reported at 220-270, >350, and 490 Å (the latter value involves synthetic samples). Al, Fe²⁺, and Fe³⁺ may substitute for Mg, and Fe³⁺ may substitute for Si; all substitutions are very limited, but greater than in lizardite. The differences between these substitutions in lizardite vs. chrysotile suggest that in natural systems, lizardite and chrysotile are not sensu stricto polymorphs. Chrysotile, or “white asbestos”, is the asbestosform serpentine and is mined in Russia near the Ural Mountains and in Asbestos, Quebec, Canada.

Substances that close a wound by scar formation; substances that heal (e.g., by healing clays).
Syn., cicatrize

A dioctahedral phyllosilicate where the vacancy is ordered and occurs in the octahedral site where the OH,F anions reside on adjacent corners of the octahedron (i.e., cis orientation). Alternatively, the description of the cis site is off the mirror plane (based on the idealized layer symmetry, not necessarily the structure in its entirety) of the layer.
Cf., transvacant

A naturally occurring material composed primarily of fine-grained minerals, which is generally plastic at appropriate water contents and will harden when dried or fired. Although clay usually contains phyllosilicates, it may contain other materials that impart plasticity and harden when dried or fired. Associated phases in clay may include materials that do not impart plasticity and organic matter. Different disciplines have uniquely defined the size of clay particles, and it is for this reason that “fine grained” is used in the definition rather than a precise value. However, because of these size variations from discipline to discipline, it is important that the particle size be specified in the context of the application. (Quot Guggenheim and Martin, 1995). For definitions relating to non-clay-science applications, see Jackson (1997).

Clay birefringent fabric is a petrographic feature showing the development of oriented, “bright” clay fabrics in the groundmass. These high birefringence regions under crossed polarizers are composites of many parallel clay particles that act together to produce a cohesive pattern. In sediments and soils, clay birefringent fabrics are commonly associated with bioturbation and wetting-desiccation cycles, respectively.
See fabric.

A general petrographic term for a fine-grained (clay size) material between coarser particles and pedofeatures in sediments or soils. The term groundmass in soils is analogous to matrix in sediments and sedimentary rocks.
Syn. soil plasma, pedoplasma.