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  • basalt stone properties

    Basalt is an igneous (volcanic) rock that is low in silica content, dark in colour, and relatively rich in iron and magnesium.

    Some basalts are completely vitreous (tachylytes), and many are fine-grained and compact. However, it is typical for them to exhibit a porphyry structure, with larger crystals (phenocrystals) of olivine, auget, or feldspar in a microcrystalline matrix (earth mass).

    Olivine and augite are the most common porphyrite minerals in basalt. Plagioclase porphyry feldspar is also found. Basalt lava is often spongy or opaque; Steam cavities are filled with secondary minerals such as calcite, chlorite, and zeolite.

    Basalts can be broadly classified on a chemical and petrographic basis into two main groups: tholite and alkali basalts. The tholitic basaltic lavas feature calcified plagioclase with augite, dove or hyperstein, and olivine (rarely) as the dominant mafic minerals; Basalt without olivine is also well represented.

    Tholite basalt, which contains 45 to 63 percent silica, is rich in iron and includes tholite (basalt with calcium-poor pyroxene). They reign among the lava of mountain belts. Its flows may build up enormous plateaus, such as in the northwestern United States, the Deccan of India, and the Parana Basin in South America. Active volcanoes of Mauna Loa and Kilauea in Hawaii erupt pyroclastic lava.

    Natural alkali basalt contains olivine and, more commonly, augit diopside or titaniferous. Alkaline basalt predominates among the lava of the ocean basins and is common among the mafic lava in the foreground and backlands of the mountain belts. In the British Icelandic province, the Paleogene and Neogene lava flows in the Inner Hebrides, Antrim and the Faroe Islands include a large succession of tholite and alkali basalts.

    Minerals of the feldspathoid group occur in a large number of basaltic rocks belonging to the alkaline group; nepheline, analcime, and leucite are the most common, but haüynite is occasionally present. If nepheline completely replaces feldspar, the rock is known as nepheline basalt; If the replacement is only partial, the term nepheline-basanite is used. Similarly, there are analemese- and leucite-basalt and leucite-basalt.

    Most basalt nevlin are fine-grained rocks of very dark color and date from the early Cenozoic (65.5 million years ago to the present). It is fairly common in some parts of Germany and also occurs in the United States (as in New Mexico), Libya, Turkey, and elsewhere. Lucite basalt is found primarily in Italy, Germany, East Africa, Australia and in the United States in Montana, Wyoming, and Arizona.

    TRANSLATED FROM:
    مقاول حجر هاشمي
    حجر هاشمي
    تشطيب واجهات حجر هاشمي كريمي
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