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what is corundum

what is corundum Corundum mineral, crystalline-aluminum oxide (Al2O3), trigonal system, ditrigonal-scalenohedral. It occurs in the form of separate or intergrown into groups of barrel-shaped, dipyramidal and tabular crystals of pseudo-hexagonal appearance, isolated inclusions and ...

What is a trough?

what is a gutter? A gutter is: 1) An oblong depression, carved into something and usually intended for water drainage or for pouring something. 2) An oblong depression on the surface of the earth, in the ground. 3) A long narrow depression on the ocean floor ...