Perlite

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

Risks

• Noncombustible.
• Resistant to insects, bacteria and fungi.

Physical and Chemical 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.

Resources and Citations

• G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 641

• Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993

• Robert Fournier, Illustrated Dictionary of Practical Pottery, Chilton Book Company, Radnor, PA, 1992

• 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." Accessed 18 Aug. 2004 .