Definition of zoning
i. In ore deposits, the spatial distribution patterns of elements, minerals, or mineral assemblages.
Ref: AGI
ii. A systematic variation in the composition and/or other properties of a single crystal, due to a separation of the chemical components during crystal growth. Common in plagioclase, garnets, tourmalines and many other minerals. The higher-temperature phases of the isomorphic series typically form the core, with the lower-temperature phases toward the margin. Concentric layering is parallel to the periphery of a crystal, shown by color banding, such as in tourmaline, and by differences in optical reactions to polarized light, such as in plagioclase feldspar.
Synonym of: zonal structure
See also: undulatory extinction
iii. Sector zoning is another related crystallographically-controlled variation in chemistry, colour, optical properties and/or inclusion distribution within a crystal. Seen in many minerals, including augite, staurolite, quartz, andalusite, plagioclase, etc. (see Dowty, E., 1976, Crystal structure and crystal growth: II. sector zoning in minerals. American Mineralogist, Volume 61, pages 460-469)
iv. In a mineral deposit, the occurrence of successive minerals or elements outward from a common center.
v. The development of areas of metamorphosed rocks that may exhibit zones in which a particular mineral or suite of minerals is predominant or characteristic, reflecting the original rock composition, the pressure and temperature of formation, the duration of metamorphism, and whether or not material was added or removed.
Ref: AGI
ii. A systematic variation in the composition and/or other properties of a single crystal, due to a separation of the chemical components during crystal growth. Common in plagioclase, garnets, tourmalines and many other minerals. The higher-temperature phases of the isomorphic series typically form the core, with the lower-temperature phases toward the margin. Concentric layering is parallel to the periphery of a crystal, shown by color banding, such as in tourmaline, and by differences in optical reactions to polarized light, such as in plagioclase feldspar.
Synonym of: zonal structure
See also: undulatory extinction
iii. Sector zoning is another related crystallographically-controlled variation in chemistry, colour, optical properties and/or inclusion distribution within a crystal. Seen in many minerals, including augite, staurolite, quartz, andalusite, plagioclase, etc. (see Dowty, E., 1976, Crystal structure and crystal growth: II. sector zoning in minerals. American Mineralogist, Volume 61, pages 460-469)
iv. In a mineral deposit, the occurrence of successive minerals or elements outward from a common center.
v. The development of areas of metamorphosed rocks that may exhibit zones in which a particular mineral or suite of minerals is predominant or characteristic, reflecting the original rock composition, the pressure and temperature of formation, the duration of metamorphism, and whether or not material was added or removed.
