Indicates a soil composite that is largely organic in nature, lacks recognizable plant structures and is very darkly colored. It differs from peat in being darker, lacking plant structures and having increased mineral content. It differs from ball clay in having significantly higher organic content and in being much darker.

Soft, plastic, sticky or slippery matter, generally containing water and clay minerals derived from fine-grained soil/regolith/sediment materials. Mud is commonly composed of clay-size particles, but often contains mixtures of sand- and silt-size particles as well as microorganisms. Potter et al. (2005) considers mud a sedimentological field term for unconsolidated fine-grained sediments of any composition and consisting of 50% or more of particles smaller than 0.0063 mm (i.e., clay and silt size fractions).
Cf., see geotherapy, matured mud, pelotherapy, poultice, Udden-Wentworth scale

Therapeutic use of healing mud (hydrated clay) in an empirical way and without medical supervision for palliative or cosmetic purposes. Traditionally, mud therapy was practiced in the natural environment where the mud occurs, but this is no longer the case.
See aesthetic medicine, antibacterial clay, geotherapy, healing clay, pelotherapy, peloid

An indurated, sedimeantary clay-bearing rock with 33-65% clay-size constituents and stratification of >10 mm thickness (bedding). An individual mudrock bed may be internally massive (after Potter et al., 2005).
See clayshale, claystone, mud, mudstone, mudshale, silt, siltstone.

An indurated, sedimentary clay-bearing rock with 33-65% clay-size constituents and lamination (stratification of <10 mm thickness), after Potter et al. (2005). See clay, clayshale, claystone, mud, mudstone, mudrock, silt, siltstone.

A general term for a rock which is similar to shale but used to describe a clay-rich rock without laminations. The fraction of clay and/or silt components are not well defined. The silt component may be of major proportions.
See clay, clayshale, claystone, mud, mudrock, mudshale, silt, siltstone.

In soil science, mull is a type of humus of the A horizon, without distinct layering, and composed of organic matter intimately mixed with the fine-grained mineral fraction.
Syn., mull humus

A dioctahedral member of the true mica group. The end-member formula is KAl₂ vAlSi₃O₁₀(OH)₂ (where v = vacancy). Typical range in composition is: Si= 3.0 – 3.1, ^ivAl = 1.9 – 2.0, K = 0.7 – 1.0 (although the interlayer site is defined in true micas as I ≥ 0.85), ^viR²⁺/(^viR²⁺ + ^viR³⁺) < 0.25, ^viAl/(^viAl + ^viFe³⁺) = 0.5 – 1.0 (Rieder et al., 1998). Muscovite commonly occurs in the 2M₁ polytype, and less commonly in 1M, 3T, 1M_d, and 2M₂ forms. Muscovite is a common rock forming mineral and occurs in igneous, metamorphic, diagenetic, and weathering environments.
Cf., nanpingite, paragonite