Rock
Perlite
Perlit
A volcanic glass that swells up to 20 times when heated: raw material of lightweight building products and the white pellets in potting mixes.
Also known as: Expanded perlite (heat-expanded product) · Crude perlite (unexpanded ore)
- Popularly: Ore and raw material
- Industrial
- Important in Türkiye
In short
Perlite is a silica-rich volcanic glass that holds roughly two to five percent water. In its raw state it is a grey, dull, pearly rock; when it is heated quickly to 750–1200 °C the water turns to steam and the glass swells to as much as 20 times its volume, becoming a white, light, foamy material. This expanded perlite is used in insulation, lightweight plaster and concrete, gardening and filtration.
Photos
How does it form?
Perlite is born when silica-rich (rhyolitic) lavas cool quickly into glass. The glass often becomes perlite when obsidian takes in groundwater (hydration), leaving a stable glass that holds roughly two to five percent water. Concentric cracks that open in the glass as it cools give perlite its onion-skin texture and, when it breaks, its pearl-like beads.
Perlite mostly occurs as broad lava flows and lava domes; its deposits are linked to rhyolite volcanism and are concentrated in young volcanic regions. Obsidian and pumice belong to the same family: the first is shiny volcanic glass, the second is glass frothed up by gas, and perlite is glass that carries a noticeable amount of water.
What is it used for?
- Building and insulation: The value of expanded perlite comes from its low density, its poor conduction of heat and sound, its chemical inertness and its fire resistance. It is used in lightweight plaster and screed, lightweight concrete, ceiling tiles and loose-fill insulation; in the United States about 45 percent of expanded perlite goes into building products (USGS).
- Agriculture and gardening: Mixed into soil or soilless growing media, it holds moisture, aerates the roots and does not compact. About 15 percent of US use is horticultural (USGS).
- Filter aid: It helps filter liquids in the food, pharmaceutical and chemical industries (about 15 percent of US use).
- Industry: It is also used to insulate cold stores and liquefied-gas tanks, in fire-resistant materials, in metallurgy and in oil drilling.
In Türkiye
Türkiye is the world’s second-largest perlite producer. According to the U.S. Geological Survey (USGS) it mined about 1.4 million tons of ore in 2025; only China (1.5 million tons) is ahead, followed by Greece (0.84 million tons) and the United States (0.46 million tons). These four countries produce 92 percent of the world’s perlite. According to the USGS, Türkiye and Greece are the world’s leading perlite exporters.
According to a 2021 report by the Istanbul Mineral Exporters’ Association (İMİB), about a quarter of Türkiye’s land area is covered by volcanic rock, and its perlites are concentrated in three volcanic regions of Western, Central and Eastern Anatolia, mostly linked to rhyolitic volcanism of Tertiary to Early–Middle Quaternary age. The main deposits are Cumaovası (Menderes) and Bergama–Dikili in İzmir, Manisa and Soma, Üçsaray–Beşsaray in Eskişehir, Kütahya, Konya and Erzincan. In Nevşehir small perlite domes lie around the Acıgöl crater, and in the Sarıkamış area of Kars there are perlites, about 15 km long, formed together with young Neogene rhyolite flows. In February 2021 Türkiye had 40 perlite mining licences: 16 in İzmir and three each in Ankara, Erzincan, Erzurum and Manisa.
Reserve figures vary widely between sources. The İMİB report gives Türkiye’s total (measured, probable and possible) perlite resource as 5.7 billion tons, but its proven reserve is 57 million tons, about 8 percent of the world’s proven reserves. Türkiye exports most of its perlite as unprocessed raw ore.
What determines its value?
Perlite is an industrial raw material bought and sold by the ton. Its value depends on its expansion ratio (how much it swells when heated), grain size, the whiteness of the expanded product and the scarcity of impurities; the size of the deposit, how well it suits open-pit mining and the distance to factories matter too. Expanded perlite is light and bulky, so it is expensive to ship. According to the İMİB report, because Türkiye mostly sells raw ore, the unit value of its exports is only about a third of the world average; selling processed (expanded) product earns far more from the same ore.
This information is educational, not buying, selling or investment advice. Value varies enormously with quality and treatment.
How to recognise it
- 1
Raw perlite is a rock that ranges from light grey to dark grey or black, glassy but dull and pearly rather than shiny like obsidian.
- 2
When it breaks you can see onion-skin-like concentric cracks and small pearl-like beads; the name comes from this look.
- 3
Mohs hardness is 5–6 and density is about 2.2–2.4 g/cm³, so it is much heavier than pumice and sinks in water.
- 4
Heated quickly to a very high temperature (750–1200 °C), it swells into a white, light foam; this is the most distinctive trait that separates it from other volcanic glasses.
Fakes and imitations
What shops usually don’t tell you:
- Obsidian is also volcanic glass, but it does not contain as much water as perlite; it is shiny, usually jet black and breaks with sharp edges, without perlite’s pearly lustre and onion-skin texture.
- Expanded perlite can look like the polystyrene pellets or plastic beads used in gardens. Perlite is a natural volcanic glass; it is fire-resistant and not springy but brittle.
Safety
Perlite is harmless to handle. The fine dust of raw or expanded perlite should not be breathed, however; the İMİB report states that breathing heavy dust for a long time can cause the lung disease silicosis. A dust mask should be worn for dusty work (bagging, crushing, pouring dry perlite in the garden). In the United States, the safety agency OSHA sets limits of 15 mg/m³ for total dust and 5 mg/m³ for respirable dust over an eight-hour working day.
Myths and misconceptions
MythMore than 70 percent of the world’s perlite reserves are in Türkiye.
FactThis is often said in Türkiye, but according to the İMİB report Türkiye’s proven (measured) perlite reserve is about 57 million tons, roughly 8 percent of the world’s proven reserves. Very large figures such as 5.7 billion tons also include probable and possible resources that are not yet confirmed, and the USGS gives no reserve figure for Türkiye.
MythThe white pellets used in gardening are plastic or polystyrene.
FactExpanded perlite is a natural volcanic glass that has simply been heated until it puffs up. According to MTA it is chemically quite pure and contains no fibres, nitrates, sulfates, phosphorus, heavy metals or radioactive elements.
Did you know?
When perlite is heated fast, the water inside turns to steam and puffs the glass up: raw perlite has a bulk density of about 1100 kg/m³, expanded perlite only 30–150 kg/m³.
The name comes from the French “perle”, meaning pearl, and refers to the pearl-like beads that appear when the rock breaks.
Expanded perlite is so light and bulky that it is expensive to transport, so expanding plants are usually built near where the perlite will be used rather than at the deposit. Mobile perlite plants that can be taken down and moved have even been set up at the building sites of cold stores and liquefied-gas tanks.
Where is it found?
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- Milos Island, Cyclades, Greece · Major depositAccording to Wikipedia, perlite is quarried on the island in open pits alongside bentonite and pozzolana. Greece is the world's third-largest perlite producer.
- Gyali Island, near Nisyros, Dodecanese, Greece · Known localityAccording to Wikipedia, the perlite and pumice deposits on Gyali provide much of Nisyros's wealth. The point is the general position of Nisyros.
- Xinyang area, Henan, China · Major depositChina is the world's largest perlite producer (USGS), but most of its output is consumed at home. Henan is one of China's main perlite regions.
- No Agua Peaks, Taos County, New Mexico, USA · Major depositPerlite quarries in late Cenozoic rhyolite domes. According to the USGS, New Mexico is the leading perlite-producing state of the USA. The point is the position of nearby Tres Piedras.
- Near Socorro, New Mexico, USA · Known localityOne of New Mexico's perlite sites lies in Socorro County. The point is the position of the town of Socorro.
- Cumaovası, Menderes, İzmir, Türkiye · Major depositMiocene perlite deposits stretching about 10 km between Murat Tepe and Karadağ; the ore is 25–90 m thick.
- Bergama–Dikili, İzmir, Türkiye · Known localityThe İMİB report counts the Bergama–Dikili area of İzmir among Türkiye's main perlite deposits. In February 2021, 16 of Türkiye's 40 perlite mining licences were in İzmir province.
- Nevşehir (Acıgöl area), Türkiye · Known localitySmall Plio-Quaternary perlite domes occur around the Acıgöl crater.
- Sarıkamış, Kars, Türkiye · Known localityPerlites formed together with young Neogene rhyolite flows; they extend about 15 km from around Mescitli village along the Keklik stream.
- Erzincan, Türkiye · Known localityErzincan is one of Türkiye's main perlite areas; the province held three perlite mining licences (2021).
- Eskişehir (Üçsaray–Beşsaray), Türkiye · Known localityThe İMİB report counts the Üçsaray–Beşsaray area of Eskişehir among Türkiye's main perlite deposits.
Locations are approximate to protect sites. Red dots mark places in Türkiye. Open in the big map →
Frequently asked questions
What is perlite?
Perlite is a silica-rich volcanic glass that holds roughly two to five percent water. In its raw state it is a grey, dull, pearly rock; when it is heated quickly to 750–1200 °C the water turns to steam and the glass swells to as much as 20 times its volume, becoming a white, light, foamy material. This expanded perlite is used in insulation, lightweight plaster and concrete, gardening and filtration.
What is perlite used for?
Building and insulation: The value of expanded perlite comes from its low density, its poor conduction of heat and sound, its chemical inertness and its fire resistance. It is used in lightweight plaster and screed, lightweight concrete, ceiling tiles and loose-fill insulation; in the United States about 45 percent of expanded perlite goes into building products (USGS). Agriculture and gardening: Mixed into soil or soilless growing media, it holds moisture, aerates the roots and does not compact. About 15 percent of US use is horticultural (USGS).
How hard is perlite?
It has a hardness of 5–6 on the Mohs scale. It can scratch glass; a steel knife scratches it only with difficulty. Its specific gravity is 2.2–2.4 g/cm³.
Where is perlite found?
Its best-known localities: Milos Island, Cyclades, Greece; Xinyang area, Henan, China; No Agua Peaks, Taos County, New Mexico, USA; Cumaovası, Menderes, İzmir, Türkiye; Gyali Island, near Nisyros, Dodecanese, Greece.
Where is perlite found in Türkiye?
Known localities in Türkiye: Cumaovası, Menderes, İzmir, Türkiye; Bergama–Dikili, İzmir, Türkiye; Nevşehir (Acıgöl area), Türkiye; Sarıkamış, Kars, Türkiye; Erzincan, Türkiye; Eskişehir (Üçsaray–Beşsaray), Türkiye.
How can you tell if perlite is real?
Raw perlite is a rock that ranges from light grey to dark grey or black, glassy but dull and pearly rather than shiny like obsidian. When it breaks you can see onion-skin-like concentric cracks and small pearl-like beads; the name comes from this look. Mohs hardness is 5–6 and density is about 2.2–2.4 g/cm³, so it is much heavier than pumice and sinks in water. Obsidian is also volcanic glass, but it does not contain as much water as perlite; it is shiny, usually jet black and breaks with sharp edges, without perlite’s pearly lustre and onion-skin texture.
Is perlite valuable?
On the “street to diamond” value ladder it sits on step 2 of nine: Raw material by the tonne. Perlite is an industrial raw material bought and sold by the ton. Its value depends on its expansion ratio (how much it swells when heated), grain size, the whiteness of the expanded product and the scarcity of impurities; the size of the deposit, how well it suits open-pit mining and the distance to factories matter too. Expanded perlite is light and bulky, so it is expensive to ship. According to the İMİB report, because Türkiye mostly sells raw ore, the unit value of its exports is only about a third of the world average; selling processed (expanded) product earns far more from the same ore.
Is perlite dangerous?
Perlite is harmless to handle. The fine dust of raw or expanded perlite should not be breathed, however; the İMİB report states that breathing heavy dust for a long time can cause the lung disease silicosis. A dust mask should be worn for dusty work (bagging, crushing, pouring dry perlite in the garden). In the United States, the safety agency OSHA sets limits of 15 mg/m³ for total dust and 5 mg/m³ for respirable dust over an eight-hour working day.
Sources
- Türkiye'de Perlit Yataklarının Durumu, İşletmeciliği ve Geleceği (Türkiye İçin Önem Arz Eden Madenler Çalışması) · İstanbul Maden İhracatçıları Birliği (İMİB), 2021
- Perlit · MTA Genel Müdürlüğü, Bilgi Merkezi
- Mineral Commodity Summaries 2026: Perlite · U.S. Geological Survey, 2026
- Perlite · Wikipedia
- Perlit · Vikipedi
- Milos · Wikipedia
- Nisyros · Wikipedia
- Perlite mining and reclamation in the No Agua Peaks, Taos County, New Mexico (Ennis) · New Mexico Geological Society, 2011
- Comprehensive Utilization and Development Strategy of Perlite Mineral Resources in China · Geological Review (cgsjournals.com)
External links
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