词条 | Scoria | ||||||
释义 |
ComparisonsScoria differs from pumice, another vesicular volcanic rock, in having larger vesicles and thicker vesicle walls, and hence is denser. The difference is probably the result of lower magma viscosity, allowing rapid volatile diffusion, bubble growth, coalescence, and bursting. FormationAs rising magma encounters lower pressures, dissolved gases are able to exsolve and form vesicles. Some of the vesicles are trapped when the magma chills and solidifies. Vesicles are usually small, spheroidal and do not impinge upon one another; instead they open into one another with little distortion. Volcanic cones of scoria can be left behind after eruptions, usually forming mountains with a crater at the summit. An example is Maungarei in New Zealand, which like Te Tatua-a-Riukiuta in the south of the same city has been extensively quarried. Quincan, a unique form of Scoria, is quarried at Mount Quincan in Far North Queensland, Australia. UsesScoria has several useful characteristics that influence how it is used. It is somewhat porous, has high surface area and strength for its weight, and often has striking colours. Scoria is often used in landscaping and drainage works.[3] It is also commonly used in gas barbecue grills.[4] Scoria can be used for high-temperature insulation. Scoria is used on oil well sites to limit mud issues with heavy truck traffic. The quarry of Puna Pau on Rapa Nui/Easter Island was the source of a red-coloured scoria which the Rapanui people used to carve the pukao (or topknots) for their distinctive moai statues, and to carve some moai from. It is also used as a traction aid on ice- and snow-covered roads. ImagesSee also
References1. ^Jackson, J.A., J. Mehl, and K. Neuendorf (2005) Glossary of Geology American Geological Institute, Alexandria, Virginia. 800 pp. {{ISBN|0-922152-76-4}} 2. ^McPhie, J., M. Doyle, and R. Allen (1993) Volcanic Textures A guide to the interpretation of textures in volcanic rocks Centre for Ore Deposit and Exploration Studies, University of Tasmania, Hobart, Tasmania..198 pp. {{ISBN|9780859015226}} 3. ^Three Kings Quarry, Winstone Aggregates. 4. ^Rock Types and Rocks Found in Michigan 2 : Volcanic rocks|Glass in nature |
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