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Metaluminous rocks are igneous rocks that have a molar proportion of aluminium oxide lower than the combination of calcium oxide, sodium oxide and potassium oxide. [1] This contrasts with peraluminous rocks in which the aluminium oxide concentration is higher than the combination, and peralkaline rocks where the alkalis are higher.
One such example is the School of Art, Media, and Design located in Singapore. This school has a roof made completely of grass (an example of Earth-sheltering). [4] This allows the use of less concrete and other materials for the roof, and the building also includes many windows to utilize natural lighting.
There are many different methods of shaping stone into useful tools. Early knappers could have used simple hammers made of wood or antler to shape stone tools. The factors that contribute to the knapping results are varied, but the EPA (exterior platform angle) indeed influences many attributes, such as length, thickness and termination of ...
In geology, silicification is a petrification process in which silica-rich fluids seep into the voids of Earth materials, e.g., rocks, wood, bones, shells, and replace the original materials with silica (SiO 2). Silica is a naturally existing and abundant compound found in organic and inorganic materials, including Earth's crust and mantle ...
The log structure was made at least 476,000 years ago, while the wood tools are slightly younger, under 400,000 years old. That places the materials in a time before our species, Homo sapiens ...
A thermite reaction using iron(III) oxide. The sparks flying outwards are globules of molten iron trailing smoke in their wake. In the following example, elemental aluminum reduces the oxide of another metal, in this common example iron oxide, because aluminum forms stronger and more stable bonds with oxygen than iron:
A metamorphic rock called emery that is mostly made of corundum which is an aluminum oxide. This is an example of an aluminum deposit. Aluminum is the third most abundant element in the lithosphere at 82,000 ppm. It occurs in low levels, 0.9 ppm, in humans. [1] Aluminum is known to be an ecotoxicant and expected to be a health risk to people.
[19] [20] [21] While this has been shown to work, archaeologists have yet to discover an actual spoon made of magnetite in a Han tomb. [ 22 ] Based on his discovery of an Olmec artifact (a shaped and grooved magnetic bar) in North America, astronomer John Carlson suggests that lodestone may have been used by the Olmec more than a thousand years ...