Online and so on - detailed definition of stomatal basalts and almond basalts
The basalt structure is related to its consolidation environment. Land on behalf of the formation of basalt, often rope-like structure, massive structure and columnar joint; underwater formation of basalt, often pillow-like structure. The stomatal structure, almond structure may appear in a variety of basalt.
The degree of crystallinity of basalt and the size of grains are mainly determined by the magma cooling rate. Slow cooling (such as a few times a day to cool down) can produce a few millimeters in size, and other large crystals; rapid cooling (such as 100 ℃ per minute cooling), you can produce small needle, plate crystal or amorphous glass. Therefore, under the surface conditions, basalt is usually fine to aphanitic or vitreous structure, a small number of medium-grain structure. Often containing olivine, pyroxene and plagioclase porphyry, constitute a patchy structure. Porphyry in the flow of magma can be gathered, called the spot structure. These porphyries are formed during the basaltic magma through the crustal rise (which lasts several months to several hours) and can also be formed in the huge magma reservoir before the eruption. The structure of the matrix varies greatly. With the thickness of the rock stream, the speed of cooling and the amount of volatile components, there are various transitional types between the whole crystal and the vitreous, but mainly the grain structure, the interstitial structure, , Less sub-green structure and bright green structure.
Basalt is the main component of sodium aluminosilicate or calcium aluminosilicate, the silica content is about 45-52%, also contains high iron oxide and magnesium oxide, is a fine dense black rock. Due to the eruption when a large number of pores, sometimes large holes such as almond-like structure, and later often filled with other minerals. This is the stomatal basalt and almond basalt.
