The next time you snag a window seat on an airline flight, check out the planeâs wing. There is a good chance the tip of the wing will be angled upward, almost perpendicular. Or it might bend smoothly up like the tip of an eagleâs wing in flight. Though obviously more complex, these wing modifications have the same aerodynamic function as the folded wingtips of a paper airplane.
scoria - the scum formed by oxidation at the surface of molten metals. slag, dross. scum - a film of impurities or vegetation that can form on the surface of a liquid. basic slag - slag produced in making steel; low in silica but having large amounts of calcium phosphate; useful as fertilizer.
Most pumice is acidic/felsic in composition associated with rhyolite since those lavas tend to have more volatiles, but intermediate and basic varieties are known to occur. Scoria is a much heavier ropey volcanic rock with larger but less prolific vesicles than pumice. There are many uses for pumice as it is light weight, relatively hard and can have very sharp edges. It is used in the cosmetics industry as an exfoliating pad, scouring stones and as an additive in creams and lotions.