odinite [mineral] . A silky green, 1:1 serpentine type clay mineral that is intermediate between dioctahedral and trioctahedral: (Fe3+,Mg,Al,Fe2+)2.4(Si,Al)2O5(OH)4. It crystallizes in trigonal and monoclinic polytypes. Apparently it forms in association with organic material on shallow marine shelves and reef lagoons in tropical latitudes (Bailey, 1988).
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.
micro- (mi'-cro-). A prefix meaning "small". When modifying a rock name, it signifies fine-grained hypabyssal, as in microgranite. Cf: macro-.
garbenschiefer (gar'-ben-schief''-er). (a) feather amphibolite. (b) A type of spotted slate characterized by concretionary spots whose shape resembles that of a caraway seed. Etymol: German. Cf: knotenschiefer; fleckschiefer; fruchtschiefer.
uralite (ur'-al-ite). A green, generally fibrous or acicular variety of secondary amphibole (hornblende or actinolite) occurring in altered rocks and pseudomorphous after pyroxene (such as augite).
inactive volcano (in-ac'-tive). A volcano that has not been known to erupt. Cf: active volcano; dormant volcano; extinct volcano.
pingguite . A yellowish-green orthorhombic mineral: Bi6(Te4+)2O13.
cutter [karst] . A solution-widened fracture. Depths range up to tens of meters. It may or may not be soil covered. Cf: karren; grike.
plane jet . A flow pattern characteristic of hyperpycnal inflow, in which the inflowing water spreads as a parabola whose width is about three times the square root of the distance downstream from the mouth (Moore, 1966, p.87). Cf: axial jet.
cyclic terrace . One of several stream terraces representing former valley floors formed during periods when downcutting had essentially stopped for a time and lateral erosion had become dominant; e.g. a valley-plain terrace. Terraces on opposite sides of the valley are paired or correspond in altitude along any given section of the valley. Cf: noncyclic terrace.
hole [streams] . (a) A deep place in a stream. (b) A water hole in the bed of an intermittent stream.