Perlite

File:Perlite-nps-02316.jpg 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 kg/m³ (1.1 g/cm³), while typical expanded perlite has a bulk density of about 30–150 kg/m³ (0.03–0.150 g/cm³).{{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 }}

• 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)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.

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Perlite is a non-renewable resource. The world reserves of perlite are estimated at 700 million tonnes.{{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}}

The confirmed resources of perlite existing in Armenia amount to 150 million m³, whereas the total amount of projected resources reaches up to 3 billion m³.{{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}} Considering specific density of 1.1 ton/m³ 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.{{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}}{{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}}

Perlite world production, led by China, Turkey, Greece, USA, Armenia and Hungary, summed up to 4.6 million tonnes in 2018.

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

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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.

In the construction and manufacturing fields, it is used in lightweight plasters, concrete and mortar, insulation and ceiling tiles.Wallace P. Bolen [http://minerals.usgs.gov/minerals/pubs/commodity/perlite/myb1-2009-perli.pdf Perlite] USGS 2009 Minerals Yearbook It may also be used to build composite materials that are sandwich-structuredMd 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. or to create syntactic foam.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.

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 foundries, cryogenic insulation, and ceramics (as a clay additive).{{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 }} It is also used by the explosives industry.[http://www.freepatentsonline.com/4940497.html Emulsion explosive composition containing expanded perlite] United States Patent 4940497

Perlite is an excellent 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}}

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.{{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}}

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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 and low water retention and helps prevent soil compaction.{{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}}

Perlite is used in cosmetics as an absorbent and mechanical exfoliant.{{Cite web|title=Perlite|url=https://www.lorealparisusa.com/ingredient-library/perlite.aspx|access-date=2020-10-04|publisher=L'Oréal}}{{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}} {{Col-begin}}

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Perlite can be replaced for all of its uses. Substitutes include:{{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}}

• Diatomite, used for filter-aids
• 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

As perlite contains silicon dioxide, goggles and silica filtering masks are recommended when handling large quantities.

The Occupational Safety and Health Administration (OSHA) has set the legal limit (permissible exposure limit) for perlite exposure in the workplace as 15 mg/m³ total exposure and 5 mg/m³ 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 mg/m³ total exposure and 5 mg/m³ respiratory exposure over an 8-hour workday.{{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}}

• Biochar
• Foam glass
• Industrial minerals
• Mortar (firestop)
• Vermiculite

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• [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. 136.
• [https://www.cdc.gov/niosh/npg/npgd0491.html CDC – NIOSH Pocket Guide to Chemical Hazards]

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Category:Felsic rocks

Category:Vitreous rocks

Category:Building stone

Category:Soil improvers

Category:Industrial minerals