Editing Perlite

{{short description|Amorphous volcanic glass}}
{{for|the two-phased structure in steel|pearlite}}
[[File:Schultz Horticultural Perlite.jpg|thumb|upright=1.3|Expanded horticultural perlite]]
'''Perlite''' is an [[amorphous]] [[volcanic glass]] that has a relatively high [[water]] content, typically formed by the [[Hydrate|hydration]] of [[obsidian]]. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently. It is an [[industrial minerals|industrial mineral]], suitable "as ceramic flux to lower the [[sintering]] temperature", and a commercial product useful for its low density after processing.<ref name=reka19>{{cite journal |last1=Reka |first1=Arianit A. |last2=Pavlovski |first2=Blagoj |last3=Lisichkov |first3=Kiril |last4=Jashari |first4=Ahmed |last5=Boev |first5=Blažo |last6=Boev |first6=Ivan |last7=Lazarova |first7=Maja |last8=Eskizeybek |first8=Volkan |last9=Oral |first9=Ayhan |last10=Makreski |first10=Petre |title=Chemical, mineralogical and structural features of native and expanded perlite from Macedonia |journal=Geologia Croatica |date=24 October 2019 |volume=72 |issue=3 |pages=215–221–215–221 |doi=10.4154/gc.2019.18 |url=http://www.geologia-croatica.hr/index.php/GC/article/view/gc.2019.18 |access-date=4 January 2020 |language=en |issn=1333-4875|doi-access=free }}</ref>

==Properties==
[[File:Perlite-nps-02316.jpg|thumb|Perlite boulders with [[fireweed]] in foreground]]
Perlite softens when it reaches temperatures of {{convert|850|–|900|°C}}. Water trapped in the structure of the material vaporises 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&nbsp;kg/m<sup>3</sup> (1.1 g/cm<sup>3</sup>), while typical expanded perlite has a bulk density of about 30–150&nbsp;kg/m<sup>3</sup> (0.03–0.150 g/cm<sup>3</sup>).<ref>{{Cite journal|title = Perlite toxicology and epidemiology – a review|journal = Inhalation Toxicology|date = 2014-04-01|issn = 0895-8378|pmc = 4002636|pmid = 24601903|pages = 259–270|volume = 26|issue = 5|doi = 10.3109/08958378.2014.881940|first1 = L. Daniel|last1 = Maxim|first2 = Ron|last2 = Niebo|first3 = Ernest E.|last3 = McConnell| bibcode=2014InhTx..26..259M }}</ref>

==Typical analysis==
*70–75% [[silicon dioxide]]: SiO<sub>2</sub>
*12–15% [[aluminium oxide]]: Al<sub>2</sub>O<sub>3</sub>
*3–4% [[sodium oxide]]: Na<sub>2</sub>O
*3–5% [[potassium oxide]]: K<sub>2</sub>O
*0.5-2% [[iron oxide]]: Fe<sub>2</sub>O<sub>3</sub>
*0.2–0.7% [[magnesium oxide]]: MgO
*0.5–1.5% [[calcium oxide]]: CaO
*3–5% loss on ignition (chemical / combined water)<ref>Md Arifuzzaman and H. S. Kim, "Prediction and evaluation of density and volume fractions for the novel perlite composite affected by internal structure formation", Construction and Building Materials, Vol 141, 2017, 201–215.</ref>
{{Clear}}

==Sources and production==
[[File:Perlite-mine.jpg|thumb|Perlite mine in Owens Valley, California.]]
Perlite is a non-renewable resource. The world reserves of perlite are estimated at 700 million [[tonne]]s.<ref>{{Cite web |last1=Celik |first1=Atila Gurhan |last2=Kilic |first2=Ahmet Mahmut |last3=Çakal |first3=Gaye Ö. |date=2013-02-27 |title=Expanded perlite aggregate characterization for use as a lightweight construction raw material |url=https://www.researchgate.net/publication/278069817 |access-date=2024-05-29 |website=Research Gate}}</ref>

The confirmed resources of perlite existing in [[Armenia]] amount to 150 million m<sup>3</sup>, whereas the total amount of projected resources reaches up to 3 billion m<sup>3</sup>.<ref>{{Cite web|url=http://www.minenergy.am/en/page/472|title=General Information - Mining Resources - www.minenergy.am|website=www.minenergy.am|access-date=2019-06-10}}</ref> Considering specific density of 1.1 ton/m<sup>3</sup> confirmed reserves in Armenia amount to 165 million tons.

Other reported reserves are: Greece - 120 million tonnes, Turkey, USA and Hungary - about 49-57 million tonnes.<ref name="Bennett">{{Cite web|url=https://prd-wret.s3-us-west-2.amazonaws.com/assets/palladium/production/atoms/files/mcs-2019-perli.pdf |archive-url=https://web.archive.org/web/20191224124414/https://prd-wret.s3-us-west-2.amazonaws.com/assets/palladium/production/atoms/files/mcs-2019-perli.pdf |archive-date=2019-12-24 |url-status=live|title=USGS Mineral Commodity Summaries - PERLITE|last=M. Bennett|first=Shawnna|website=U.S. Geological Survey, Mineral Commodity Summaries}}</ref><ref name="USGS">{{Cite web|url=https://www.usgs.gov/centers/nmic/perlite-statistics-and-information|title=Perlite Statistics and Information|website=www.usgs.gov|access-date=2019-06-10}}</ref>

Perlite world production, led by China, Turkey, Greece, USA, Armenia and Hungary, summed up to 4.6 million tonnes in 2018.<ref name="Bennett" /><ref name="USGS" />

[[Patanvav|Osham hills of Patanvav, Gujarat, India]] are the only source of mineral Perlite in India.

{{Anchor|Production and application}}

== Uses ==
Because of its low density and relatively low price (about US$150 per tonne of unexpanded perlite), many commercial applications for perlite have been developed.

=== Construction and manufacturing ===
In the [[construction]] and manufacturing fields, it is used in lightweight [[plaster]]s, concrete and [[mortar (masonry)|mortar]], [[Thermal insulation|insulation]] and ceiling tiles.<ref name="usgs">Wallace P. Bolen [http://minerals.usgs.gov/minerals/pubs/commodity/perlite/myb1-2009-perli.pdf Perlite] USGS 2009 Minerals Yearbook</ref> It may also be used to build [[composite materials]] that are [[Sandwich structured composite|sandwich-structured]]<ref>Md Arifuzzaman and H. S. Kim, Novel flexural behaviour of sandwich structures made of perlite foam/sodium silicate core and paper skin, Construction and Building Materials, Construction and Building Materials, Vol 148 2017, pp 321–333.</ref> or to create [[syntactic foam]].<ref>Dipendra Shastri and H. S. Kim, “A new consolidation process for expanded perlite particles”, Construction and Building Materials, Vol 60, June, 2014, pp.1–7.</ref>

Perlite filters are fairly common in filtering [[beer]] before it is bottled.{{citation needed|date=March 2021}}

Small quantities of perlite are also used in [[foundry|foundries]], [[cryogenic]] insulation, and [[ceramics (art)|ceramics]] (as a clay additive).<ref>{{cite journal |last1=Moradi |first1=L. |last2=Mirzaei |first2=M. |title=Immobilization of Lewis acidic ionic liquid on perlite nanoparticle surfaces as a highly efficient solid acid catalyst for the solvent-free synthesis of xanthene derivatives |journal=RSC Advances |date=2019 |volume=9 |issue=35 |pages=19940–19948 |doi=10.1039/c9ra03312b|pmid=35514727 |pmc=9065349 |bibcode=2019RSCAd...919940M }}</ref> It is also used by the explosives industry.<ref>[http://www.freepatentsonline.com/4940497.html Emulsion explosive composition containing expanded perlite] United States Patent 4940497</ref>

=== Aquatic filtration ===
Perlite is an excellent [[Filtration#Filter aid|filtration aid]] and is used extensively as an alternative to [[diatomaceous earth]]. The popularity of perlite usage as a filter medium is growing considerably worldwide.{{citation needed|date=February 2024}} Several products exist in the market to provide perlite based filtration. Several perlite filters and perlite media have met NSF-50 approval (Aquify PMF Series and AquaPerl), which standardizes water quality and technology safety and performance. Perlite can be safely disposed of through existing sewage systems, although some pool operators choose to separate the perlite using settling tanks or screening systems to be disposed of separately.{{citation needed|date=September 2021}}

=== Biotechnology ===
Due to thermal and mechanical stability, non-toxicity, and high resistance against microbial attacks and organic solvents, perlite is widely used in biotechnological applications.  Perlite was found to be an excellent support for immobilization of biocatalysts such as enzymes for [[bioremediation]] and sensing applications.<ref>{{Cite journal|last1=Torabi|first1=Seyed-Fakhreddin|last2=Khajeh|first2=Khosro|last3=Ghasempur|first3=Salehe|last4=Ghaemi|first4=Nasser|last5=Siadat|first5=Seyed-Omid Ranaei|date=2007-08-31|title=Covalent attachment of cholesterol oxidase and horseradish peroxidase on perlite through silanization: Activity, stability and co-immobilization|journal=Journal of Biotechnology|volume=131|issue=2|pages=111–120|doi=10.1016/j.jbiotec.2007.04.015|pmid=17658643}}</ref>

=== Agriculture ===
[[File:Trowel.jpg|thumb|Perlite mixed into potting compost]]
In [[horticulture]], perlite can be used as a [[soil amendment]] or alone as a medium for [[hydroponics]] or for starting [[Cutting (plant)|cuttings]]. When used as an amendment, it has high permeability and low water retention and helps prevent [[Soil compaction (agriculture)|soil compaction]].<ref>{{cite web|title=ISU Extension News Release|url=http://www.extension.iastate.edu/newsrel/2004/feb04/feb0429.html|url-status=dead|archive-url=https://web.archive.org/web/20040323003156/http://www.extension.iastate.edu/newsrel/2004/feb04/feb0429.html|archive-date=2004-03-23|work=iastate.edu}}</ref>

=== Cosmetics ===
Perlite is used in cosmetics as an absorbent and mechanical [[Exfoliation (cosmetology)|exfoliant]].<ref>{{Cite web|title=Perlite|url=https://www.lorealparisusa.com/ingredient-library/perlite.aspx|access-date=2020-10-04|publisher=[[L'Oréal]]}}</ref><ref>{{Cite book|last=Winter|first=Ruth|url=https://books.google.com/books?id=3hLmyma2-MsC&q=perlite&pg=PA402|title=A Consumer's Dictionary of Cosmetic Ingredients, 7th Edition: Complete Information About the Harmful and Desirable Ingredients Found in Cosmetics and Cosmeceuticals|date=2009-10-20|publisher=Potter/Ten Speed/Harmony/Rodale|isbn=978-0-307-45986-2|pages=402|language=en}}</ref> {{Col-begin}}
{{Col-break}}
{| class="wikitable"
|-
! colspan=2 | Estimated perlite consumption <br />in the U.S. by application<ref name=usgs2>[http://minerals.usgs.gov/minerals/pubs/commodity/perlite/mcs-2011-perli.pdf Perlite], USGS Mineral Commodity Summaries 2011</ref>
|-
! Fraction !! Use<ref name="usgs2008">{{cite web|url=http://minerals.usgs.gov/minerals/pubs/commodity/perlite/mcs-2008-perli.pdf |archive-url=https://web.archive.org/web/20080514063904/http://minerals.usgs.gov/minerals/pubs/commodity/perlite/mcs-2008-perli.pdf |archive-date=2008-05-14 |url-status=live|title=PERLITE : (Data in thousand metric tons unless otherwise noted)|website=Minerals.usgs.gov|access-date=22 October 2017}}</ref>
|-
| 53% || building construction products
|-
| 14% || horticultural aggregate
|-
| 14% || fillers
|-
| 8% || filter aid
|-
| 11% || other
|}
{{Col-break}}
{| class="wikitable" style="text-align:center; width:200px; height:200px;"
! colspan=2 | Cost of unexpanded perlite<ref>{{cite journal
 |date=January 2006
 | title = Perlite
 | journal = U.S. Geological Survey Mineral Commodity Summaries
 | pages = 122–123
 | url =http://minerals.usgs.gov/minerals/pubs/commodity/perlite/perlimcs06.pdf}}</ref>
|-
! End of<br/>year !! Price in the U.S.<br/>$ per [[Metric ton|metric&nbsp;ton]]
|-
| 2001 || $36.30
|-
| 2002 || $36.50
|-
| 2003 || $38.20
|-
| 2004 ||  $41.80<ref name="usgs"/>
|-
| 2005 ||  $40.50<ref name="usgs"/>
|-
| 2006 || $42.90
|-
| 2007 || $45.30
|-
| 2008 || $48.00
|-
| 2009 || $49.00
|}
{{col-end}}

===Substitutes===
Perlite can be replaced for all of its uses. Substitutes include:<ref name="usgs2013">{{citation|title=USGS Mineral Commodity Summaries|url=http://minerals.usgs.gov/minerals/pubs/commodity/perlite/mcs-2013-perli.pdf |archive-url=https://web.archive.org/web/20130528025129/http://minerals.usgs.gov/minerals/pubs/commodity/perlite/mcs-2013-perli.pdf |archive-date=2013-05-28 |url-status=live|year=2013}}</ref>
*[[Diatomaceous earth|Diatomite]], used for filter-aids
*[[Expanded clay aggregate|Expanded clay]], an alternative lightweight filler for building materials
*[[Shale]]
*[[Pumice]]
*[[Slag]]
*[[Vermiculite]] - many expanders of perlite are also exfoliating vermiculite and belong to both trade associations

== Occupational safety ==
As perlite contains [[silicon dioxide]], goggles and silica filtering masks are recommended when handling large quantities.

=== United States ===
The [[Occupational Safety and Health Administration]] (OSHA) has set the legal limit ([[permissible exposure limit]]) for perlite exposure in the workplace as 15&nbsp;mg/m<sup>3</sup> total exposure and 5&nbsp;mg/m<sup>3</sup> respiratory exposure over an 8-hour workday. The [[National Institute for Occupational Safety and Health]] (NIOSH) has set a [[recommended exposure limit]] (REL) of 10&nbsp;mg/m<sup>3</sup> total exposure and 5&nbsp;mg/m<sup>3</sup> respiratory exposure over an 8-hour workday.<ref>{{cite web|title = CDC – NIOSH Pocket Guide to Chemical Hazards – Perlite|url = https://www.cdc.gov/niosh/npg/npgd0491.html|website = www.cdc.gov|access-date = 2015-11-27}}</ref>

==See also==
*[[Biochar]]
*[[Foam glass]]
*[[Industrial minerals]]
*[[Mortar (firestop)]]
*[[Vermiculite]]

==References==
{{reflist}}

==External links==
{{commons category}}
*[http://www.perlite.org The Perlite Institute]
*[https://web.archive.org/web/20050808082154/http://www.mii.org/Minerals/photoperlite.html Mineral Information Institute – perlite]
*[https://books.google.com/books?id=yt0DAAAAMBAJ&dq=1954+Popular+Mechanics+January&pg=PA136 "That Wonderful Volcanic Popcorn."] ''Popular Mechanics'', December 1954, p.&nbsp;136.
*[https://www.cdc.gov/niosh/npg/npgd0491.html CDC – NIOSH Pocket Guide to Chemical Hazards]

{{Authority control}}

[[Category:Felsic rocks]]
[[Category:Vitreous rocks]]
[[Category:Building stone]]
[[Category:Soil improvers]]
[[Category:Industrial minerals]]