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Igneous rock (igneous from Latin igneus 'fiery'), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in either a planet's mantle or crust.
The oldest rocks visible in Devils Tower National Monument were laid down in a shallow sea during the Triassic. [citation needed] This dark red sandstone and maroon siltstone, interbedded with shale, can be seen along the Belle Fourche River. Oxidation of iron minerals causes the redness of the rocks. This rock layer is known as the Spearfish ...
El Señor de las Limas, the largest known greenstone sculpture, Xalapa Museum Greenstone staff, 1550 - 1600 AD, from the Tairona culture of present-day Colombia.. Greenstone is a common generic term for valuable, green-hued minerals and metamorphosed igneous rocks and stones which early cultures used in the fashioning of hardstone carvings such as jewelry, statuettes, ritual tools, and various ...
About 65% of the Earth's crust by volume consists of igneous rocks. Of these, 66% are basalt and gabbro, 16% are granite, and 17% granodiorite and diorite. Only 0.6% are syenite and 0.3% are ultramafic. The oceanic crust is 99% basalt, which is an igneous rock of mafic composition.
The Giant's Causeway (Irish: Clochán an Aifir) [1] is an area of approximately 40,000 interlocking basalt columns, the result of an ancient volcanic fissure eruption. [3] [4] It is located in County Antrim on the north coast of Northern Ireland, about three miles (4.8 km) northeast of the town of Bushmills.
A rock cut temple is carved from a large rock and excavated and cut to imitate a wooden or masonry temple with wall decorations and works of art. Pancha Rathas is an example of monolith Indian rock cut architecture dating from the late 7th century located at Mamallapuram, a UNESCO World Heritage Site.
Bornhardts are commonly composed of igneous rocks, [4] often granites, [4] [5] but examples of gneiss, quartzite and arkose bornhardts exist. [5] The Sugarloaf Mountain of Rio de Janeiro is a typical example of this landform and is the origin of the common bornhardt nickname "sugar loaf". [6]
Thus porphyry was prized for monuments and building projects in Imperial Rome and thereafter. Subsequently, the name was given to any igneous rocks with large crystals. The adjective porphyritic now refers to a certain texture of igneous rock regardless of its chemical and mineralogical composition or its color. Its chief characteristic is a ...