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Related to Andesite: Andesite line


Very finely crystalline extrusive rock of volcanic origin composed largely of plagioclase feldspar (oligoclase or andesine) with smaller amounts of dark-colored mineral (hornblende, biotite, or pyroxene), the extrusive equivalent of diorite.



an extrusive, dark-colored (such as dark gray, brown, or black) mountain rock. Its structure is porphyritic or hyalopilitic; in the latter case the microlites resemble felt saturated with glass. It is formed as a result of the freezing, at the top surface or close to it, of volcanic lava containing 56–60 percent silicic acid and much magnesium, calcium, and iron. Andesite is usually a fresh rock composed of crystals of medium plagioclases, andesine, and pyroxenes and less frequently of magnetite, hornblende, and other minerals immersed in glass. Andésite is widely spread throughout contemporary and ancient volcanic regions such as Kamchatka, the Caucasus, Middle Asia, and the Mediterranean. Together with basalt, it constitutes the principal mass of extrusive rocks. It is used as an acid-proof material and for special glazing.

References in periodicals archive ?
Some studies have been carried out recently to use andesite as a coating material and raw material in the ceramics sector.
H2O] values of -6 to -5[per thousand] at 300 [degrees]C as does coexisting secondary feldspar and chlorite for andesite sample CBI-6-6-52 (Fig.
La pierre de construction du parement du batiment initial est une roche volcanique dacitique gris pale a grains fins, communement appelee andesite de l'ile Haddington.
The find has sparked debate about how the tool arrived in the Midlands as andesite only occurs in the Lake District and North Wales.
Tying in with that suggestion, the latest analysis of another rock, Yogi, indicates that it, too, may contain andesite, says Harry Y.
Inclined working hosted in agilically altered Andesite
It intersected siliceous breccia with a few small intervals of chloritized andesite and lapilli tuff and gold values from top to bottom.
faulted and is intruded by dacite and andesite porphyry dykes and rare
The andesite rock in the Cheviot area formed 395-370 million years ago.
The axe, which is made of andesite - a type of volcanic rock - would have been used by our ancestors for butchering animals and is only the ninth such tool found in the Midlands in more than a century of investigation.
Les Fyffe provides a new interpretation of stratigraphy in the Eel River area of west-central New Brunswick, and shows that volcanic rocks in the area include andesite and likely formed in an arc environment.
Photo: Andesite spire marks approach to North Butte summit for hikers on guided outing Day-hikes usually last from early morning until near sunset.