striped ground . A form of patterned ground marked by alternating stripes produced on a sloping surface by frost action. See also: sorted stripe. Syn: striped soil; striated ground.
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.
tourmaline (tour'-ma-line). (a) A group of minerals of general formula: (Na,Ca)(Mg,Fe2+,Fe3+,Al,Li)3Al6(OH)4(BO3)3[Si6O 18`]. It sometimes contains fluorine in small amounts. (b) Any of the minerals of the tourmaline group, such as buergerite, elbaite, and dravite. Tourmaline occurs in 3-, 6-, or 9-sided prisms, usually vertically striated, or in compact or columnar masses; it is commonly found as an accessory mineral in granitic pegmatites, and is widely distributed in acid igneous rocks and in metamorphic rocks. Its color varies greatly and gives a basis for naming the varieties; when transparent and flawless, it may be cut into gems. See also: schörl; elbaite. Also spelled: turmaline.
ammonioleucite . A white tetragonal mineral: (NH4,K)(Si2Al)O6. The ammonium-dominant analogue of leucite.
mine . n. (a) An underground excavation for the extraction of mineral deposits, in contrast to surficial excavations such as quarries. The term is also applied to various types of open-pit workings. (b) The area or property of a mineral deposit that is being excavated; a mining claim. v. To excavate for and extract mineral deposits or building stone.
coeruleolactite (coe-ru''-le-o-lac'-tite). A triclinic mineral: (Ca,Cu)Al6(PO4)4(OH)8•4-5H2O . It has a milk-white to sky-blue color, and is a member of the turquoise group.
creta (cre'-ta). chalk. Etymol: Latin, "chalk".
transtensional fault (trans-ten'-sion-al). A strike-slip fault across which there is a component of extension. The extension may lead to the development of negative flower structure .
dilation (di-la'-tion). Deformation by a change in volume but not shape. Also spelled: dilatation.
crawlway (crawl'-way). A cave passage that is traversable only by crawling.
hydrocerussite (hy''-dro-ce-rus'-site). A colorless or lightly tinted rhombohedral mineral: Pb3(CO3)2(OH)2 . It occurs as a secondary product as an encrustation on native lead or on galena.
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