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Definitions

American Heritage® Dictionary of the English Language, Fourth Edition

  1. n. A banded or foliated metamorphic rock, usually of the same composition as granite.

Century Dictionary and Cyclopedia

  1. n. A rock which consists essentially of the same mineral elements as granite, namely orthoclase, quartz, and mica, but in which there is a more or less distinctly foliated arrangement of the constituent minerals, and especially of the mica. It appears in a great variety of forms, and shows all stages of passage from true granite to a perfectly schistose condition, in which case the feldspar disappears, and the rock becomes a true mica schist. Porphyritic gneiss is characterized by the presence of large distinct crystals or rounded kernel-like masses of feldspar. Gneiss often contains hornblende instead of or associated with mica, and then receives the name of hornblendic or syenitic gneiss. Some gneisses are undoubtedly of eruptive origin; other varieties are admitted by most geologists to be metamorphosed sedimentary masses. As is the case with granite, so in gneiss the orthoclase is sometimes associated with plagioclase. See granite.

Wiktionary

  1. n. A common and widely-distributed metamorphic rock having bands or veins.

GNU Webster's 1913

  1. n. A crystalline rock, consisting, like granite, of quartz, feldspar, and mica, but having these materials, especially the mica, arranged in planes, so that it breaks rather easily into coarse slabs or flags. Hornblende sometimes takes the place of the mica, and it is then called hornblendic gneiss or syenitic gneiss. Similar varieties of related rocks are also called gneiss.

WordNet 3.0

  1. n. a laminated metamorphic rock similar to granite

Etymologies

  1. German Gneis, probably alteration of Middle High German ganeist, spark (from its appearance), from Old High German gneista.

Examples

  • “The stratified gneiss, which is the underlying rock of much of this part of the country, dips toward the centre of the continent, but the strata are often so much elevated as to appear nearly on their edges.”

    Missionary Travels and Researches in South Africa

  • “Unfortunately, no such thing as earth or gravel existed in which to sink these posts, and the rock being of the variety known as gneiss, was more than ordinarily tough.”

    The Home of the Blizzard Being the Story of the Australasian Antarctic Expedition, 1911-1914

  • “All these minerals have once been imbedded in the granitic gneiss, which is the principal rock of the region.”

    The Voyage of the Vega round Asia and Europe, Volume I and Volume II

  • “Many of these rocks are much crumpled, others quite flat, and they are overlaid by soft, variegated gneiss, which is continued alternately with the slates to the top of the hills on the opposite side.”

    Himalayan Journals — Complete

  • “The prevalent north-east strike of the gneiss is the same in both, differing from the Himalaya, where the stratified rocks generally strike north-west.”

    Himalayan Journals — Complete

  • “On re-ascending from Punkabaree, the rocks gradually appear more and more dislocated, the clay-slate less so than the quartz and mica-schist, and that again far less than the gneiss, which is so shattered and bent, that it is impossible to say what is _in situ, _ and what not.”

    Himalayan Journals — Complete

  • “In one place the latter rock is seen bursting through the gneiss, which is slaty and very crystalline at the junction.”

    Himalayan Journals — Complete

  • “_ The bungalow stands on soft, contorted, decomposing gneiss, which is still the prevalent rock, striking north-east.”

    Himalayan Journals — Complete

  • “In the black gneiss, which is at the bottom, the wall may stand above the river for a few hundred yards or a mile or two; then, to follow the foot of the wall, you must pass into a lateral canyon for a long distance, perhaps miles, and then back again on the other side of the lateral canyon; then along by the river until another lateral canyon is reached, which must be headed in the black gneiss.”

    Canyons of the Colorado

  • “Soils are weathered from a variety of crystalline and metamorphic materials, such as gneiss, schist, and granite, as well as some areas of igneous intrusive rocks.”

    Ecoregions of New Mexico (EPA)

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‘gneiss’ has been looked up 2101 times, loved by 2 people, added to 26 lists, commented on 3 times, and has a Scrabble score of 7.