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Photomicrograph of thin section of latite (in plane polarised light) Photomicrograph of thin section of latite (in cross polarised light) Latite is an igneous, volcanic rock, with aphanitic-aphyric to aphyric-porphyritic texture. It is the volcanic equivalent of monzonite.
Porphyritic texture in a granite. This is an intrusive porphyritic rock. The white, square feldspar phenocrysts are much larger than crystals in the surrounding matrix; eastern Sierra Nevada, Rock Creek Canyon, California. A porphyritic volcanic sand grain, as seen under the petrographic microscope. The large grain in the middle is of a much ...
Thin section of garnet mica schist from Salangen, Norway. A garnet porphyroblast (black) contains curved trails of small inclusions (white and grey). Some garnet porphyroblasts contain curving trails of quartz and other mineral inclusions that record rotation of the crystals relative to their surroundings.
In hand specimen, many of the hornblende and biotite dacites are grey or pale brown and yellow rocks with white feldspars, and black crystals of biotite and hornblende. Other dacites, especially pyroxene-bearing dacites, are darker colored. [4] In thin section, dacites may have an aphanitic to porphyritic texture.
Esterellite is a porphyritic rock, completely crystalline, containing large phenocrysts (plagioclases, quartz, ferromagnesians), which are very visible to the naked eye, and a matrix of very small microcrystals.
Thin sections are prepared in order to investigate the optical properties of the minerals in the rock. This work is a part of petrology and helps to reveal the origin and evolution of the parent rock. A photograph of a rock in thin section is often referred to as a photomicrograph.
Igneous textures include the rock textures occurring in igneous rocks. Igneous textures are used by geologists in determining the mode of origin of igneous rocks and are used in rock classification. The six main types of textures are phaneritic, aphanitic, porphyritic, glassy, pyroclastic, and pegmatitic.
Overall, the granite is a porphyritic rock that is composed of plagioclase feldspar, quartz, and biotite, and contains large pink microcline chunks throughout the matrix. The microcline megacrysts appear as blocky, subhedral grains that are generally around 2 cm in length, but can range from 1 to 4 cm.