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. It is an industrial mineral, suitable "as ceramic flux to lower the sintering temperature", and a commercial product useful for its low density after processing. It is also used as a soil conditioner in horticulture.

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, suitable "as ceramic flux to lower the sintering temperature", and a commercial product useful for its low density after processing. It is also used as a soil conditioner in horticulture. ==Properties== in foreground Perlite softens when it reaches temperatures of . 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/m 3 (1.1 g/cm 3 ), while typical expanded perlite has a bulk density of about 30–150 kg/m 3 (0.03–0.150 g/cm 3 ). ==Typical analysis== 70–75% silicon dioxide: SiO 2 12–15% aluminium oxide: Al 2 O 3 3–4% sodium oxide: Na 2 O 3–5% potassium oxide: K 2 O 0.5-2% iron oxide: Fe 2 O 3 0.2–0.7% magnesium oxide: MgO 0.5–1.5% calcium oxide: CaO 3–5% loss on ignition (chemical / combined water) ==Sources and production== Perlite is a non-renewable resource. The world reserves of perlite are estimated at 700 million tonnes. The confirmed resources of perlite existing in Armenia amount to 150 million m 3 , whereas the total amount of projected resources reaches up to 3 billion m 3 . Considering specific density of 1.1 ton/m 3 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. 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. The largest landslide in Icelandic history (the Loðmundarskriður in Loðmundarfjörður) was assisted by the mountain's high perlite composition. Plans to mine and export the perlite in the mid 20th century fell through. ===Substitutes=== Perlite can be replaced for all of its uses. Substitutes include: 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 ==See also== Biochar Foam glass Industrial minerals Mortar (firestop) Vermiculite ==References== ==External links== The Perlite Institute Mineral Information Institute – perlite "That Wonderful Volcanic Popcorn." Popular Mechanics, December 1954, p. 136. CDC – NIOSH Pocket Guide to Chemical Hazards

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