Web12 apr. 2024 · Most of the primary biotite with shreddy and ragged textures appears to be re–equilibrated by hydrothermal fluids during the formation of potassic alteration (Fig. 6i, j). Primary euhedral to subhedral magmatic biotite is mostly altered to greenish–brown secondary biotite, fine–grained chlorite (20–100 μm), muscovite, and Fe oxy–hydroxides … Web7 jul. 2024 · Porphyrys are formed by a two-stage cooling of rising magma. First, deep crustal magma cools slowly, allowing formation of large phenocrysts (diameter 2 mm or more). What is porphyritic texture and how is it interpreted? Porphyritic texture is an igneous rock texture in which large crystals are set in a finer-grained or glassy …

What does porphyritic texture indicate? - TimesMojo

Web3 sep. 2024 · Their texture is between plutonic and volcanic igneous rocks, and they commonly form on sills, laccoliths, and dykes. These rocks have an intermediate or medium grain size and porphyritic texture. Examples include diabase, diorite, and microgranite. How to classify them depends on their grain size. Examples of phaneritic rocks WebPorphyritic texture may be caused by any one or more of the following factors: (i) Difference in Molecular Concentration: When the magma is rich in molecules of a particular mineral, the latter has better chance to grow into big crystals which may get embedded in the fine-grained mass resulting from the deficient components. phoenix to flagstaff driving

Porphyritic Granite Geology 1501 ECU

Webtrachyte, light-coloured, very fine-grained extrusive igneous rock that is composed chiefly of alkali feldspar with minor amounts of dark-coloured minerals such as biotite, amphibole, or pyroxene. Compositionally, trachyte is the volcanic equivalent of the plutonic (intrusive) rock syenite. Most trachytes show porphyritic texture in which abundant, large, well-formed … Webtrachyte, light-coloured, very fine-grained extrusive igneous rock that is composed chiefly of alkali feldspar with minor amounts of dark-coloured minerals such as biotite, amphibole, … WebRocks with equally distributed grain size (also called seriate) may sometimes appear to be composed of phenocrysts and groundmass because this is what our brain sees. A seriate rock will have large and small crystals, and usually you will have lots of small crystals sitting just next to the big ones. phoenix to glamis ca