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Volcano Into Water Where:
Expanded perlite is established as a competitor to diatomite. Perlite is a rock with volcanic origins, being formed from molten lava that erupted from a volcano into water where it was quenched and rapidly cooled. It is a supercooled liquid or natural glass comprising a mass of small 'pebbles' which may be up to about 25 mm in diameter, but which are generally about 2 //m or smaller. Occluded in the particles is a small amount of water, giving the mineral a water content of 3-^4%.Like earthquakes, volcanoes continue to wreak destruction and death. In recent years, however, man has learned much of the causes of volcanic eruption from the instrumentation of the Kilauea volcano on the island of Hawaii. Constant watch by a U.S. Geological Survey team has revealed a consistent cycle of activity by this volcano.
The composite volcano develops a form which :• dominated by rock fragments exploded from :tie throat, interspersed with lava flows from '.his vent or from fissures in the side of the moun-:ain. A volcano of this type is normally steeply •loping and symmetrical, with a small crater in ae top. The crater is a funnel-shaped depression »'hich rarely exceeds a mile or so in diameter. Many composite volcanoes rise 10,000 feet or more above their base. Mayon Volcano in the Philippine Islands, Vesuvius in Italy, and Fuji in japan are good examples of composite volcanoes. The great majority of high places on the alobc which are called mountains are composed!rd sedimentary rocks.
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