The first thing one would look at is if there are minerals present that are large enough to either be identified with the naked eye or with a handlense. Most lavas have large volumes of extremely finegrained material or glass whereas plutonic rocks that mostly crystallize in depths of several kilometers are usually composed of millimeter sized minerals. Further differentiation of ejecta can be done like (ash, lapilli, volcanic bombs, pahoehoe-lava etc.).
One can then look at the mineralogical composition of these rocks to define whether they are basic (little silicon) like basalts/gabbros or acid (a lot of silicon) like rhyolites/granites. The usual classification is the QAPF-diagram (quarz, alkali feldspar, plagioclase, feldspathoid), which is composed of two ternary diagrams. If quarz is present the ternary diagram including quarz is used, otherwise the one with an feldspathoid endmember is chosen for classification.
This field description is then usually followed by a series of lab analyses of the chemical and isotopic composition of the rock in order to be classified via their elemental composition. One example is the TAS-diagram (total alkali elements versus silicon dioxide content).
From this often confusing situation, a commonly used classification for igneous rocks has emerged based on two criteria--texture and chemical composition. Texture refers to the size of crystals, presence of glass, and porosity of the rock. Texture is determined primarily by how the magma or lava cooled. Following are common textural terms for igneous rocks.
Intrusive and extrusive factors of an igneous rock classify them. The other factors are if they are vesicular, coarse, fine grained, glassy, or very coarse
Extrusive (cooling of lava/magma above the earths surface) and Intrusive (cooling of lava/magma below the earth's surface)
Texture and crystal size
Texture and composition.
Composition and Texture
Formed by gaseous fire
crystal size
youre mom
If u are at a science class and do this for homework, I'm glad that I gave you then answer, it took me 10 minute to figure out It's Composition
The percentage of its composition of silica.
colorstreakhardnesscleavage or fracturelustermagnetismdensitycrystal shape
Intrusive and extrusive factors of an igneous rock classify them. The other factors are if they are vesicular, coarse, fine grained, glassy, or very coarse
crystal size
Color and texture is one way to classify igneous rocks. Another way to do this is modal classification and normative classification.
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i have no clue!
This substance is silicon dioxide.
yes,either felsic if light coloured or mafic if dark cloured.we classify rocks like that especially igneous rocks but COLOR IS NEVER USED TO IDENTIFY ANY ROCK.only classification.
igneous rocks are used for blilding and for long lasting moument.
Extrusive igneous rocks i think are used for carving and awesome things like that!
the 3 ways igneous rocks are used are in schools,houses and roads. this is because they are hard,igneous rocks make useful road building materials
If u are at a science class and do this for homework, I'm glad that I gave you then answer, it took me 10 minute to figure out It's Composition
The melting and cooling of a metamorphic rock will allow it to turn into an Igneous rock.