Encyclopedia > Perlite

  Article Content

Perlite

Perlite is an amorphous glass mineral of volcanic origin.

Typical analysis: 70-75% SiO2, 12-15% Al2O3, Na2O 3-4%, K2O 3-5%, Fe2O<sub2>3</sub> 0,5-2%, MgO 0,2-0,7%, CaO 0,5-1,5% Loss On Ignition 3-5%

Properties: When it reaches temperatures of 850-900C, perlite softens (since it is a glass) and water trapped in the structure escapes and this causes the expansion of the material at 7-15 times its original volume. The expanded material is a brilliant white, due to the reflectivity of the trapped bubbles. Unexpanded ("raw") perlite bulk density: around 1100 kg/m3 (1,1 gr/cm3) Typical expanded perlite bulk density: 30-150 kg/m3

Due to the low density of expanded perlite it has many uses: Lightweight plasters and mortars, insulation, ceiling tiles. In horticulture it makes composts more open to air, while still having good water-retention properties; it makes a good medium for hydroponics.

See also:

List of minerals
Vermiculite



All Wikipedia text is available under the terms of the GNU Free Documentation License

 
  Search Encyclopedia

Search over one million articles, find something about almost anything!
 
 
  
  Featured Article
Northwest Harbor, New York

... of the population are Hispanic or Latino of any race. There are 1,181 households out of which 33.8% have children under the age of 18 living with them, 55.2% are married ...

 
 
 
This page was created in 36.3 ms