Perlite

Perlite

Perlite is an amorphous volcanic glass that has a relatively high water content, typically formed by the hydration of obsidian. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently.

Properties and uses

When it reaches temperatures of 850–900 °C, perlite softens (since it is a glass). Water trapped in the structure of the material vapourises and escapes and this causes the expansion of the material to 7–16 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 g/cm³).
Typical expanded perlite bulk density: 30–150 kg/m³

Due to its low density and relatively low price, many commercial applications for perlite have developed. In the construction and manufacturing fields, it is used in lightweight plasters and mortars, insulation, ceiling tiles and filter aids. In horticulture it makes composts more open to air, while still having good water-retention properties; it makes a good medium for hydroponics. Perlite is also used in foundries, cryogenic insulations, as a lightweight aggregate in mortar (firestop) and in ceramics as a clay additive.

Typical analysis of perlite

*70-75% silicon dioxide: SiO2
*12-15% aluminium oxide: Al2O3
*3-4% sodium oxide: Na2O
*3-5% potassium oxide: K2O
*0.5-2% iron oxide: Fe2O3
*0.2-0.7% magnesium oxide: MgO
*0.5-1.5% calcium oxide: CaO
*3-5% loss on ignition (chemical / combined water)

Production trends

In 2005, Greece was the top producer of perlite with at least one-third world share followed by China, USA, Japan and Turkey [Reported by the British Geological Survey] .

In 2001 the cost of perlite was about US$36.31 per metric ton. The yearend price for mined perlite in the US has increased since then [cite journal
author =
year = 2006
month = January
title = Perlite
journal = U.S. Geological Survey Mineral Commodity Summaries,
volume =
issue =
pages = 122–123
id = [http://minerals.usgs.gov/minerals/pubs/commodity/perlite/perlimcs06.pdf] ] ::2001.....$36.3 per metric ton:2002.....$36.5 per metric ton:2003.....$38.2 per metric ton:2004.....$40.6 per metric ton:2005.....$42.5 per metric ton

ee also

*Vermiculite (Many expanders of perlite are also exfoliating vermiculite and belong to both trade associations)
*Diatomite (used for filter-aids)
*Industrial minerals
*Mortar (firestop)

References

External links

* [http://www.perlite.org The Perlite Institute]
* [http://www.perlite.info Perlite Information Source]
* [http://www.incon-corp.com Manufacturer of Perlite Expansion Equipment]
* [http://www.mii.org/Minerals/photoperlite.html Mineral Information Institute - perlite]


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Look at other dictionaries:

  • perlite — [ pɛrlit ] n. f. • 1812; de perle 1 ♦ Minér. Silicate naturel, pauvre en eau, de la famille des feldspaths. 2 ♦ (v. 1960) Techn. Constituant microscopique des alliages ferreux. Fonte à perlite. ● perlite nom féminin (de perle) Rhyolite vitreuse… …   Encyclopédie Universelle

  • Perlite — Per lite, n. (Min.) Same as {Pearlite}. [1913 Webster] …   The Collaborative International Dictionary of English

  • perlite — [pʉr′līt΄] n. [Fr < perle,PEARL1] 1. Geol. a greenish volcanic glass, similar to obsidian, with a pearly luster and multiple, minute concentric cracks, used as insulation and in making concrete, plaster, etc. 2. PEARLITE perlitic [pər lit′ik]… …   English World dictionary

  • perlite — perlitic /perr lit ik/, adj. /perr luyt/, n. Petrog. a volcanic glass in which concentric fractures impart a distinctive structure resembling masses of small spheroids, used as a plant growth medium. Also, pearlite. [1825 35; < F; see PEARL1,… …   Universalium

  • Perlite — Perlit (vulkanisches Glas) mit weißem, pudrigen Aussehen Perlit (englisch: perlite) bezeichnet in den Geowissenschaften ein alteriertes (chemisch und physikalisch umgewandeltes) vulkanisches Glas (Obsidian) und zählt damit zu den Gesteinen. Die… …   Deutsch Wikipedia

  • Perlite — Cette page d’homonymie répertorie les différents sujets et articles partageant un même nom. La perlite est un constituant biphasé de l acier. La perlite est une roche naturelle à base de silice. Catégorie : Homonymie …   Wikipédia en Français

  • perlite — per·lì·te s.f. 1. TS petr. roccia effusiva acida costituita principalmente da vetro disposto in concrezioni simili a perle che si formano durante il raffreddamento, utilizzata come isolante termoacustico 2. TS metall. eutettico di ferrite e… …   Dizionario italiano

  • perlite — GLOSSARY OF VOLCANIC TERMS Hydrated obsidian, generally light grey in color, that is commonly characterized by rounded, onion skin like fractures (perlitic cracks). Apache s tears are unhydrated clumps of fresh obsidian that are commonly found… …   Glossary of volcanic terms

  • perlite —   n. volcanic glass forming, when expanded by heat, an insulating material and a light weight aggregate added to concrete and plaster or used as soil conditioner.    ♦ perlitic, a. having perlite like texture …   Dictionary of difficult words

  • perlite — perlitas statusas T sritis chemija apibrėžtis Kaitinant išpūsti, 5–20 kartų padidėję rūgščiosios vulkaninės uolienos grūdeliai atitikmenys: angl. pearlite; perlite rus. перлит …   Chemijos terminų aiškinamasis žodynas

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