There are 2 or more very distinct grain sizes.
The smaller grains are called phenocrysts and
the material around it is called matrix or
groundmass. The phenocrysts are 0.3 - 5 mm.
To truly see what a porphyritic texture looks like
just search on Google images and you'll see a nice
example along with a diagram that explains it.
Granite rock is not porphyritic. It is phaneritic because it has a coarse-grained texture.
It's texture is porphyritic
Rhyolite may be aphanitic or porphyritic.
Porphyritic
A porphyritic texture can be a feature of igneous rocks, but 'porphyritic' is not used to describe metamorphic rock texture. Metamorphic rocks can be foliated or non-foliated, terms used to describe mineral alignment or banding, or the lack thereof.
Granite rock is not porphyritic. It is phaneritic because it has a coarse-grained texture.
It's texture is porphyritic
Rhyolite may be aphanitic or porphyritic.
Porphyritic
Typically porphyritic with hbl phenocrysts.
A porphyritic texture can be a feature of igneous rocks, but 'porphyritic' is not used to describe metamorphic rock texture. Metamorphic rocks can be foliated or non-foliated, terms used to describe mineral alignment or banding, or the lack thereof.
The igneous texture characterized by two distinctively different crystal sizes is known as porphyritic texture. Porphyritic rocks have larger crystals (phenocrysts) surrounded by a fine-grained matrix (groundmass), indicating two different stages of cooling within the magma.
A porphyritic texture is displayed in an igneous rock containing large isolated crystals (phenocrysts) in a mass of fine textured crystals . Porphyritic texture indicates that a magma has gone through a two stage cooling process. The magma has cooled sufficiently underground to allow some minerals to crystallize and grow in size; the magma is then expelled above ground where the remaining liquid magma solidifies quickly, allowing only small crystals to develop.See link below for a picture of a porphyritic texture in a rock.
There are 2 or more very distinct gain sizes. The smaller grains are called phenocrysts and the material around it is called matrix or groundmass. The phenocrysts are 0.3 - 5 mm. To truly see what a porphyritic texture looks like just search on google images and you'll see a nice example along with a diagram that explains it.
The resulting texture is porphyritic. The slower cooling stage allows large crystals to form (phenocrysts), while the faster cooling stage results in the formation of smaller crystals in the remaining magma (groundmass). This gives the rock a mixture of large and small crystals, creating a porphyritic texture.
Correct, porphyritic texture is typically associated with igneous rocks and is not a common feature of sedimentary rocks. It is characterized by larger crystals, known as phenocrysts, surrounded by a fine-grained or glassy matrix. Sedimentary rocks are formed through the accumulation and lithification of sediments, which do not typically undergo the same crystallization processes as igneous rocks.
You cannot determine the age of a "texture". There are numerous methods for dating the age of rocks. Go to Geology.com and search for rock dating methods.