ferrinatrite (fer-ri-nat'-rite). A grayish-white or whitish-green trigonal mineral: Na3Fe3+(SO4)3•3H2O .
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.
pressure penitente . A nieve penitente composed of brilliantly white ice, shaped into a slender ridge by lateral pressure of converging morainal streams and by melting of the adjacent debris-covered ice (Workman, 1914, p.316-317). Such features have broken upper surfaces and sharply inclined sides (resembling pointed cones, wedges, or pyramids), and usually occur on the lower parts of glaciers where morainal streams are strongly developed.
terskite (ter'-skite). A pale lilac orthorhombic mineral: Na4ZrSi6O15(OH)2•H2O .
aillikite . In the IUGS classification (Woolley et al., 1996) this dike rock is reclassified as a carbonatite rather than an ultramafic carbonate-rich lamprophyre . Obsolete.
tafone (ta-fo'-ne). (a) A Corsican dialect term for one of the natural cavities in a honeycomb structure, formed by cavernous weathering on the face of a cliff in a dry region or along the seashore. The hole or recess may reach a depth of 10 cm, and is explained as due to solution of free salts in crystalline rock (granite, gneiss) following heating by insolation. (b) A granitic or gneissic block or boulder hollowed out by cavernous weathering. Pl: tafoni.
ripple cross-lamination . Small-scale cross-lamination formed by migrating current ripples developed during deposition, characterized by individual laminae whose thicknesses range between 0.08 cm (1/32 in.) and 0.3 cm (1/8 in.) (McKee, 1939, p.72). See also: ripple lamina. Syn: rolling strata.
gamma [magnet] . The cgs unit of magnetic field intensity: 1 gamma = 10-5 gauss = 10-9 tesla. It has been replaced in magnetic exploration by the SI preferred name of nanotesla (nT).
introgression (in-tro-gres'-sion). The evolutionary process in which a hybrid [evol] crosses with a member of one of its parental species, thus introducing some genes from the other parental species into the next generation of the first species. Syn: introgressive hybridization.
vishnevite (vish'-nev-ite). A pale lilac, light blue, or dark gray mineral of the cancrinite group: (Na,Ca,K)8(AlSiO4)6O24(SO4)•2H2O .
drift [coast] . Detrital material moved and deposited by waves and currents; e.g. littoral drift. Also, floating material (e.g. driftwood or seaweed; flotsam) that has been washed ashore by waves and left stranded on a beach.
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