2007-09-04 16:39:39 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Earth Sciences & Geology
Porphyritic texture indicates that an igneous rock had some time to cool before being extruded onto the surface of the Earth. Another way to develop a porphyritic texture is to intrude an igneous rock into a near surface environment, allowing the magma to cool more quickly than deeper environments. These are call hypabyssal intrusions.
2007-09-05 04:32:07 · answer #1 · answered by Amphibolite 7 · 1⤊ 0⤋
What the top contributor did not do was answer your question, despite her encyclopedic definition of porphyritic texture. The only way to get a texture like this in an igneous rock is for it to cool very slowly giving the large crystals time to grow. This is a sign of an intrusive igneous rock probably formed deep underground.
2007-09-04 17:26:04 · answer #2 · answered by utarch 5 · 1⤊ 1⤋
Put it simply, porphyritic texture are indicative of slow cooling from a molten state giving enough time for the mineral crystals to grow. These mineral crystals are bigger in size from the groundmass or the enclosing minerals. In contrast, fine grained rock texture or equi-granular texture are rocks that have more or less the same size of small minerals due to abrupt cooling from a molten state having no time to grow crystals.
2007-09-04 21:57:12 · answer #3 · answered by deo 3 · 1⤊ 0⤋