perlite
American Heritage Dictionary:
Top
per·lite
also pearl·ite (pûr'līt') 
n.
A natural volcanic glass similar to obsidian but having distinctive concentric cracks and a relatively high water content. In a fluffy heat-expanded form perlite is used as a lightweight aggregate, in fire-resistant insulation, and in soil for potted plants.
n.
A natural volcanic glass similar to obsidian but having distinctive concentric cracks and a relatively high water content. In a fluffy heat-expanded form perlite is used as a lightweight aggregate, in fire-resistant insulation, and in soil for potted plants.
[French (from perle, pearl , from Old French; see pearl1) or German Perlite (from Perle, pearl , ultimately from Vulgar Latin *pernula).]
perlitic per·lit'ic (pər-lĭt'ĭk) adj.Britannica Concise Encyclopedia:
Top
perlite
Natural glass with concentric cracks such that the rock breaks into small, pearl-like bodies. It is formed by the rapid cooling of viscous lava or magma. Perlite is porous and has a waxy to pearly lustre and is commonly gray or greenish but may be brown, blue, or red. Since 1950, large deposits have been worked in New Mexico, Nevada, California, and other western states. Heat-treated perlite is a substitute for sand in lightweight wall plaster and concrete aggregate. Perlite is used for heat and sound insulation, lightweight ceramic products, and filters.
For more information on perlite, visit Britannica.com.
A siliceous volcanic rock; under heat it expands to 15 to 20 times its original volume, forming an excellent lightweight aggregate; used in plaster or gypsum wallboard, as loose-fill thermal insulation, and as an aggregate in concrete.
Top
A white, grasslike, volcanic mineral, about one-tenth the weight of sand, that is useful as a medium for rooting cuttings but lacks any nutrients. Perlite is also often added to soilless potting mixes.
Random House Word Menu:
Top
categories related to 'perlite'
- Practice, Tools, and Techniques - perlite: light, porous soil additive composed of volcanic material
Wikipedia on Answers.com:
Top
Perlite
For the two-phased structure in steel, see pearlite.
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. It is an industrial mineral and a commercial product useful for its light weight after processing.
|
Contents
|
Properties
When it reaches temperatures of 850–900 °C, perlite softens (because 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 has a bulk density around 1100 kg/m3 (1.1 g/cm3), while typical expanded perlite has a bulk density of about 30–150 kg/m3.
Production and uses
Perlite is a non-renewable resource. The world reserves of perlite are estimated at 700 million tonnes. In 2011, 1.7 million tonnes had been produced, mostly by Greece (500,000 t), United States (375,000 t) and Turkey (220,000 t); however, no information for China – a leading producer – was available.[1]
Because of its low density and relatively low price (about US$50 per tonne of unexpanded perlite), many commercial applications for perlite have developed. In the construction and manufacturing fields, it is used in lightweight plasters and mortars, insulation and ceiling tiles.[2]
In horticulture, perlite can be used as a soil amendment or alone as a medium for hydroponics or for starting cuttings. When used as an amendment it has high permeability / low water retention and helps prevent soil compaction.
Perlite is an excellent filter aid. It is used extensively as an alternative to diatomaceous earth. The popularity of perlite usage in this application is growing considerably worldwide. Perlite filters are fairly commonplace in filtering beer before it is bottled.
Small quantities of perlite are also used in foundries, cryogenic insulation, as a lightweight aggregate in mortar (firestop) and in ceramics as a clay additive. It is also used by the explosive industry.[3]
In 2010, estimated perlite consumption in the US was as shown in the table:[1]
| Fraction | use[2] |
|---|---|
| 53% | building construction products |
| 14% | horticultural aggregate |
| 14% | fillers |
| 8% | filter aid |
| 11% | other |
The cost of unexpanded perlite has varied since 2001.[4]:
| end of year |
Price in the US $ per t |
|---|---|
| 2001 | 36.3 |
| 2002 | 36.5 |
| 2003 | 38.2 |
| 2004 | 41.8[2] |
| 2005 | 40.5[2] |
| 2006 | 42.9 |
| 2007 | 51.6 |
| 2008 | 60.0 |
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)
See also
- Biochar (The large surface area of carbon molecules increases the soil structure, aeration, nutrient and water retention capacity. Biochar creates a healthy soil in which micro-organisms thrive.)
- 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
 |
Wikimedia Commons has media related to: Perlite |
- The Perlite Institute
- Mineral Information Institute – perlite
- Perlite in Turkey World %68 Deposits in Turkey
- "That Wonderful Volcanic Popcorn." Popular Mechanics, December 1954, p. 136.
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
Post a question - any question - to the WikiAnswers community:
Copyrights:
American Heritage Dictionary
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
Read more
Britannica Concise Encyclopedia
Britannica Concise Encyclopedia. © 1994-2012 Encyclopædia Britannica, Inc. All rights reserved. Read more
McGraw-Hill Dictionary of Architecture & Construction
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc. All rights reserved.
Read more
Taylor's Dictionary for Gardeners
Taylor's Dictionary for Gardeners, by Frances Tenenbaum. Copyright © 1997 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
Read more
Random House Word Menu
© 2010 Write Brothers Inc. Word Menu is a registered trademark of the Estate of Stephen Glazier.
Write Brothers Inc.
All rights reserved.
Read more
