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Gneiss - Wikipedia


Gneiss is a common distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks. It is often fol...

What type of rock has light and dark layers - Answers.com


A rock has alternating layers of dark and light colors the rock has visible quartz crystals and ... What rock has parallel bands of dark and light mineral grains?

Metamorphic Rock Classification - faculty at Chemeketa


Foliation refers to flat or wavy planar features (looking like layers) caused by the ... Foliation may also look like alternating bands of light and dark minerals. In contrast, a nonfoliated rock has interlocking grains with no specific pattern. Foliated ...

Rock Key - Bob's Rock Shop


If rocks are buried deep enough, they melt. .... The rock has crystals, layers that look like ribbons or bands of minerals running through it, and is kind of blocky . It is. . . Go to ... Is the rock mostly light or medium gray, not very dark gray or black?

Chapter 4 Rocks and Minerals - Volcano World


Under the thick layers of sedimentary rock lies the denser granite. The granitic ... The lava has cooled and is now a volcanic rock called basalt. The weathering .... Biotite mica is dark green to black in color because it contains iron, magnesium. Mica is ... Some minerals sparkle in the light while others are dull and boring!!

Igneous Rocks


The word "texture" has nothing to do with how the rock feels. ... Geologists look at the proportions of light-colored and dark-colored minerals in an igneous rock to estimate the ... Each layer of sedimentary rock is like a chapter in the history of the earth. .... If these stresses do melt the original rock, an igneous rock i...



Very light-colored rocks are generally lacking in iron-bearing minerals. ... An abundance of these minerals will yield a gray to dark gray mineral. ... An important principle of geology holds that sedimentary rocks are deposited in horizontal layers. .... It is formed at great depths within the earth and has crystals ranging from ...

Metamorphic Rocks


James Hutton, a Scottish doctor became fascinated by metamorphic rocks and published .... has properties of both a gas and a liquid. Supercritical ... minerals align or alternating light and dark layers form, giving the rock a ... Distinguished based on composition, but may be foliated if subjected to ... form compositional bands.

Metamorphic Rocks


The light and dark bands (gneissic banding) are alternations of felsic vs. mafic layers. Slate is a product of low grade metamorphism (not terribly great burial ...

PA DCNR - Geology - Rock Types


Pennsylvania has had a variety of igneous rocks; however, most of these have undergone metamorphism. On the maps, they are classified simply as dark or light-colored. ... rock names are based on grain size, organization of minerals into layers ... Includes dark-colored gneiss and diabase (and kimberlite, if it is shown on ...