Word: silica
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...before Columbia or any of the three other orbiters that Rockwell International is building for NASA can undertake such projects, major problems must be overcome. One difficulty: finishing the laborious job of affixing 40,000 or so silica foam tiles to the orbiter's outer skin. These shield it from the blazing temperatures (nearly 3,000° F) that the ship will encounter when it re-enters the atmosphere and glides to a landing at either the Kennedy Space Center or Vandenberg Air Force Base in California. A more serious difficulty: ironing the bugs out of the shuttle...
...Bruces are indeed paragons of piscine verisimilitude. Their gray and white polyurethane skin, sprayed with a fine-grained silica, is authentically sandpapery enough to be the envy of all the lady sharks at sea. Their eyes dart frighteningly, then-great tails are fully articulated, and their three-way stretch jaws-with head-and-shoulder roominess-are filled with three rows of pearly polyurethane teeth...
...near Gunflint Lake in western Ontario, which somehow escaped this rough treatment. In the magazine Science, Paleontologist Elso S. Barg-hoorn-of Harvard and the late Geologist Stanley A. Tyler of the University of Wisconsin describe the remains of microscopic organisms that lived in that "Gunflint chert" - an impure silica -about 2 billion years ago, 1,800 million years before the earliest dinosaurs...
...living parts were on the tips: microscopic threads of algae tangled together, busily depositing silica that stiffened the columns. The hummocks eventually became the Gunflint chert, which radioactive dating proves to be 2 billion years...
...water above the hummocks must have teemed with tiny boating things that sank between the silica columns when they died. Those things may have been plants or animals or something in between. Whatever they were, they resembled small stars, or spheres with smaller spheres sticking to their outside walls. The most elaborate form had a bulbous base, a stalk and a ribbed cap. Its discoverers do not know whether it was sedentary like a mushroom or swam like a miniature jellyfish...