Definitions for phenocryst
ˈfi nə krɪst, ˈfɛn ə-phe·noc·ryst

WiktionaryRate this definition:0.0 / 0 votes

1. phenocrystnoun

   any relatively large crystal embedded in a more fine-grained or glassy igneous rock

WikipediaRate this definition:0.0 / 0 votes

1. Phenocryst

   A phenocryst is an early forming, relatively large and usually conspicuous crystal distinctly larger than the grains of the rock groundmass of an igneous rock. Such rocks that have a distinct difference in the size of the crystals are called porphyries, and the adjective porphyritic is used to describe them. Phenocrysts often have euhedral forms, either due to early growth within a magma, or by post-emplacement recrystallization. Normally the term phenocryst is not used unless the crystals are directly observable, which is sometimes stated as greater than .5 millimeter in diameter. Phenocrysts below this level, but still larger than the groundmass crystals, are termed microphenocrysts. Very large phenocrysts are termed megaphenocrysts. Some rocks contain both microphenocrysts and megaphenocrysts. In metamorphic rocks, crystals similar to phenocrysts are called porphyroblasts. Phenocrysts are more often found in the lighter (higher silica) igneous rocks such as felsites and andesites, although they occur throughout the igneous spectrum including in the ultramafics. The largest crystals found in some pegmatites are often phenocrysts being significantly larger than the other minerals.

WikidataRate this definition:0.0 / 0 votes

1. Phenocryst

   A phenocryst is a relatively large and usually conspicuous crystal distinctly larger than the grains of the rock groundmass of a porphyritic igneous rock. Phenocrysts often have euhedral forms either due to early growth within a magma or by post-emplacement recrystallization. Plagioclase phenocrysts often exhibit zoning with a more calcic core surrounded by progressively more sodic rinds. This zoning is reflective of the changing magma composition as crystallization progresses. In rapakivi granites phenocrysts of orthoclase are enveloped within rinds of sodic plagioclase such as oligoclase. In shallow intrusives or volcanic flows phenocrysts which formed before eruption or shallow emplacement are surrounded by a fine grained to glassy matrix. These volcanic phenocrysts often show flow banding, a parallel arrangement of lath shaped crystals. Phenocrysts are often used when the rock name is determined. For example, olivine may form the primary phenocrysts of some materials, and as such is used to define the subtype of that material. Phenocrysts are commonly found in materials such as felsite and andesite. Volcanic rocks classified according to the nature and abundance of phenocryst assemblages are often described as aphyric when fewer than 1% phenocrysts are visible with a hand lens. Porphyritic volcanic rocks are further classified by phenocryst type using mineral name modifiers given in the order of decreasing abundance. The term phenocryst is used for a crystal that is significantly larger than the average size of the groundmass crystals; in practice, these are generally >~1 mm. Thus, olivine-plagioclase phyric basalt contains >10% phenocrysts, the dominant phenocryst being olivine, with lesser amounts of plagioclase. The suffix -phyric includes all of the phenocryst phases that occur in the rock, as long as the total content >1%.

How to pronounce phenocryst?

1. Alex

   US English

   David

   US English

   Mark

   US English

   Daniel

   British

   Libby

   British

   Mia

   British

   Karen

   Australian

   Hayley

   Australian

   Natasha

   Australian

   Veena

   Indian

   Priya

   Indian

   Neerja

   Indian

   Zira

   US English

   Oliver

   British

   Wendy

   British

   Fred

   US English

   Tessa

   South African

How to say phenocryst in sign language?

Numerology

1. Chaldean Numerology

   The numerical value of phenocryst in Chaldean Numerology is: 7

2. Pythagorean Numerology

   The numerical value of phenocryst in Pythagorean Numerology is: 8

References

1. ^ Wiktionary
   https://en.wiktionary.org/wiki/Phenocryst
2. ^ Wikipedia
   https://en.wikipedia.org/wiki/Phenocryst
3. ^ Wikidata
   https://www.wikidata.org/w/index.php?search=phenocryst