Perlite
Description
1) A eutectic material formed between ferrite and cementite.
2) A type of obsidian, or natural glass, found in California that is 70-75% silica, 12-14% alumina and 6-8% alkalis. Perlite contains a high proportions of cracks, spheroids and water. When it is flash roasted to 1000 C, perlite expands to 20 times its size forming bubble-filled beads. This expanded white aggregate is then crushed and used as an extender, a fire-resistant insulator and a component in potting soil. Expanded perlite is also used to make insulating brick.
Synonyms and Related Terms
2: pearlite; pearlstone
Other Properties
Unaffected by water, acids, alkalis or organic solvents.
Luster = waxy Color= gray, green or brown (unexpanded)
Can expand 6-20 times when heated.
Expanded perlite can absorb 200-500% of its weight in liquid.
Hazards and Safety
Noncombustible. Resistant to insects, bacteria and fungi.
Authority
- G.S.Brady, G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 641
- Richard S. Lewis, Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
- Robert Fournier, Robert Fournier, Illustrated Dictionary of Practical Pottery, Chilton Book Company, Radnor, PA, 1992
- Random House, Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
- The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998
- Encyclopedia Britannica, http://www.britannica.com Comment: "Perlite." Encyclopdia Britannica. 18 Aug. 2004 .