The branch of knowledge concerned with medicinal drugs derived from natural products. This knowledge base includes the study of physical, chemical and biological properties of natural substances, for example, clays and clay minerals, used medicinally.

A part of a system with distinct chemical and physical properties that is mechanically separable from other parts of the system.

A graphical representation of the relationships involving possible phases that occur in a system, typically based on parameters such as temperature (T), pressure (P), composition (X), and typically at equilibrium conditions. However, other parameters may be used where convenient and non-equilibrium diagrams may be useful to show important phase relationships.

A series name to describe potassium-rich dioctahedral micas between or close to the muscovite-aluminoceladonite join and the muscovite-celadonite join (i.e., Al,Mg,Fe-containing).

A poorly defined material, possibly a decomposition product of biotite and vermiculite.

See zeolite.

A trioctahedral member of the true mica group. The end-member formula is KMg₃AlSi₃O₁₀(OH)₂. Fe²⁺ for Mg substitution is common nearly to the Fe end member (annite). Mn and Ti and minor V and Cu substitution is less common. Octahedral vacancies are more prevalent in Fe-containing phlogopite. Phlogopite is defined as having <50% Fe substitution for Mg along the Mg/Fe join. When Fe and Mg content have not been determined, the series name, biotite, is appropriate. Tetrahedral Al substitution tends to be limited to <1.5 cations per formula unit (Fleet, 2003) and Fe³⁺ and Ti can occupy the tetrahedral site if there is a deficiency in Si. Phlogopite commonly occurs as the 1M and 1M_d polytypes, although the 3T and 2M₁ forms are less common.

An obsolete and poorly defined term describing material from Fins, France, similar to kaolin but with apparently excess H₂O.

A poorly defined material, possibly phlogopite or saponite.

The groundwater table in soil or sediment. The phreatic surface is the interface between the vadose zone (unsaturated water content) and the phreatic zone (saturated with water) of a soil/sediment, usually characterized with a zero porewater pressure.