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porphyroblast

Line breaks: por¦phyro|blast
Pronunciation: /ˈpɔːfɪrə(ʊ)blast
 
/

Definition of porphyroblast in English:

noun

Geology
A larger recrystallized grain occurring in a finer groundmass in a metamorphic rock.
Example sentences
  • Evidence of contact metamorphism of the wall-rock includes andalusite porphyroblasts enclosed in a fabric related to Caledonian nappe emplacement.
  • Such inclusions may be aligned, preserving evidence of the fabric in the rock when the porphyroblast grew.
  • Cordierite in these two metamorphic belts forms rounded, opaque black to brown porphyroblasts typically less than 0.5 inch across.

Derivatives

porphyroblastic

1
Pronunciation: /-ˈblastɪk/
adjective
Example sentences
  • Strongly foliated porphyroblastic politic gneiss forms a selvedge up to 100 m thick in sharp (but in some cases ductile) contact with peridotite on the northern margin of the Carratraca massif.
  • The earliest porphyroblastic fabric is not restricted to the immediate metapluton surroundings.

Definition of porphyroblast in:

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