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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beef . A quarrying term, used originally in Purbeck, southern England, for thin, flat-lying veins or layers of fibrous calcite, anhydrite, gypsum, halite, or silica, occurring along bedding planes of shale, giving a resemblance to beef. It appears to be due to rapid crystallization in lenticular cavities.

knitted texture (knit'-ted). A texture that is typical of the mineral serpentine in a rock when it replaces a clinopyroxene. Cf: lattice texture [meta].

Earth tide . The response of the solid Earth to the forces that produce the tides of the sea; semidaily Earth tides have a fluctuation of between seven and fifteen centimeters (Strahler, 1963, p.110-111). Syn: bodily tide.

laqueiform (la-que'-i-form). Said of the loop pattern in a dallinid brachiopod (as in the family Laqueidae) in which posterior connecting bands from the ascending branches to the descending branches "are retained during enlargement and proportional thinning during change from frenuliniform to terebrataliiform loop" (TIP, 1965, pt. H, p.147).

sorosilicate (so-ro-sil'-i-cate). A class or structural type of silicate characterized by the linkage of two SiO4 tetrahedra by the sharing of one oxygen, with a Si:O ratio of 2:7. An example of a sorosilicate is hemimorphite, Zn4Si2O7(OH)2•H2O. Cf: nesosilicate; cyclosilicate; inosilicate; phyllosilicate; tectosilicate. Syn: double island silicate.

tertiopedate element . Asymmetric ramiform conodont element with a posterior process and a lateral process on each side of the cusp; posterior process commonly long and denticulate (TIP, 1981, pt. W, supp.2).

foshallassite (fos-hal'-las-site). A pearly snow-white mineral: Ca3Si2O7•3H2O(?) . Also spelled: foschallasite.

raindrop impact (rain'-drop). The action of raindrops striking or falling upon the surface of the ground. Syn: rainbeat.

tsumgallite . A pale greenish-yellow or beige orthorhombic mineral of the diaspore group: GaOOH.

alumino-ferro-hornblende . A green monoclinic member of the amphibole mineral family: Ca2(Fe2+4Al)(Si7Al)O22(OH)2. Probably an unnecessary name for ferrohornblende.

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