RFG 2018 Conference

GeoWord of the Day

The GeoWord of the Day is a free service of the American Geosciences Institute. All of the terms and definitions are from the Glossary of Geology, 5th Edition Revised.

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tracheid (tra'-che-id). A pitted, lignified, elongate, cylindrical cell that is the basic water-conducting and support cell in xylem tissue. Tracheids often have tapered end walls and are nonliving at maturity. Cryptogams and gymnosperms generally have only tracheids for conduction; most angiosperms also have vessels.

Clerici solution (Cle-ri'-ci). A solution of thallium malonate and thallium formate in water that is used as a heavy liquid; its specific gravity is 4.15. Cf: Sonstadt solution; Klein solution; bromoform; methylene iodide.

green beryl . A term applied to the light green or pale green gem variety of beryl, as distinguished from the full green or richly green-colored emerald and the light blue-green aquamarine.

aspidolite . An olive-green trioctahedral mica: NaMg3(Si3Al)O10(OH)2. Syn: sodium phlogopite; wonesite.

laforêtite . A metallic brown tetragonal mineral of the chalcopyrite group: AgInS2.

laforêtite . A metallic brown tetragonal mineral of the chalcopyrite group: AgInS2.

shell bank . A bank [sed] consisting largely of shells, esp. of corals and pelecypods.

influent seepage . Movement of gravity water in the unsaturated zone , from the ground surface toward the water table; seepage of water into the ground.

lukrahnite . A yellow triclinic mineral of the helmutwinklerite group: Ca(Cu,Zn)(Fe3+,Zn)(AsO4)2(OH,H2O)2.

corrugated lamination (cor'-ru-gat''-ed). A form of convolute bedding that differs from convolute lamination in that the lamination is intricately contorted and does not show a regular subparallel orientation of anticlines and synclines.

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