The American Perlite quarry is for sale!
For inquiries, please contact Albert Dalrymple
- The Perlite Institute Web Site
- USGS Minerals Information
on Perlite
- American Perlite's web site -
Perlite ore
- The Schundler Company's
web site -
Perlite on the East Coast
- Whittemore Company's
web site -
Perlite on the East Coast
- Supreme Perlite Company's
web site -
Perlite in the Northwest
- Silbrico's Web site -
Perlite in the Mid West
- Incon Corporation's web site -
Perlite furnace systems and info
- Otavi Minen AG -
Perlite in Europe
- Deutsche Perlite GmbH -
Perlite in Germany and Europe
- Nordisk Perlite -
Perlite in Norway and Europe
- Stauss Perlite and Europerl -
Perlite in Austria
- Per&Tas Metal and Perlite Inc. -
Perlite in Turkey
- Pull b.v. - -
Perlite in The Netherlands and Europe
- US Asia-Pacific Minerals -
Perlite in the Pacific Rim and Asia


Welcome to the home page of! Here you will find information about what perlite is and its many and varied applications. Additionally, you can find links to other perlite resources on the Internet on the left.

Perlite - rock, crushed, and expanded

Basic facts about perlite

Perlite is not a trade name but a generic term for naturally occurring siliceous rock. The distinguishing feature which sets perlite apart from other volcanic glasses is that when heated to a suitable point in its softening range, it expands from four to twenty times its original volume.

This expansion is due to the presence of two to six percent combined water in the crude perlite rock. When quickly heated to above 1600F (871C), the crude rock pops in a manner similar to popcorn as the combined water vaporizes and creates countless tiny bubbles which account for the amazing light weight and other exceptional physical properties of expanded perlite. Expanded Perlite - Course, Medium, & Fine

This expansion process also creates one of perlite's most distinguishing characteristics: its white color. While the crude rock may range from transparent light gray to glossy black, the color of expanded perlite ranges from snowy white to grayish white.

Expanded perlite can be manufactured to weigh as little as 2 pounds per cubic foot making it adaptable for numerous applications.

Since perlite is a form of natural glass, it is classified as chemically inert and has a pH of approximately 7.

Perlite is mined and expanded all over the world. The United States is estimated to be the largest consumer and producer of crude and expanded perlite. However, there is very strong world wide production and consumption of perlite. Other leading countries producing perlite include China, Greece, Japan, Hungary, Armenia, Italy, Mexico, Philippines, and Turkey.

Typical Elemental Analysis
Silicon 33.8
Aluminum 7.2
Potassium 3.5
Sodium 3.4
Iron 0.6
Calcium 0.6
Magnesium 0.2
Trace 0.2
Oxygen (by difference) 47.5
Net Total 97.0
Bound Water 3.0
Total 100.0
* All analyses are shown in elemental form even though the actual forms present are mixed glassy silicates. Free silica may be present in small amounts, characteristic of the particular ore body. More specific information may be obtained from the ore supplier involved.
Typical Physical Properties
Color White
Refractive Index 1.5
Free Moisture, Maximum 0.5%
pH (of water slurry) 6.5 - 8.0
Specific Gravity 2.2 - 2.4
Bulk Density (loose weight) As desired but usually in the 2-25 lb/ft3 range (32-400 kg/m3)
Mesh Size Available As desired, 4-8 mesh and finer
Softening Point 1600-2000F (871-1093C)
Fusion Point 2300-2450F (1260-1343C)
Specific Heat 0.2 Btu/lbF (387 J/kgK)
Thermal Conductivity at 75F (24C) .27-.41 Btuin/hft2F(.04-.06 W/mK)
Solubility .......Soluble in hot concentrated alkali and HF Moderately soluble (<10%) in 1N NaOH
Slightly soluble (<3%) in mineral acids (1N)
Very slightly soluble (<1%) in water or weak acids

Uses for Perlite...

There are many uses for perlite. These uses can be broken down into three general categories: construction applications, horticultural applications, and industrial applications.

Construction Applications

Conversion Table
U.S. Mesh Inches Microns MM
3 .265 6730 6.73
4 .187 4760


5 .157 4000 4.00
6 .132 3360 3.36
7 .111 2830 2.83
8 .0937 2380 2.38
10 .0787 2000 2.00
12 .0661 1680


14 .0555 1410 1.41
16 .0469 1190 1.19
18 .0394 1000 1.00
20 .0331 841 .841
25 .0280 707 .707
30 .0232 595 .595
35 .0197 500 .500
40 .0165 420 .420
45 .0138 354 .354
50 .0117 297 .297
60 .0098 250 .250
70 .0083 210 .210
80 .0070 177 .177
100 .0059 149 .149
120 .0049 125 .125
140 .0041 105 .105
170 .0035 88 .088
200 .0029 74 .074
230 .0024 63 .062
270 .0021 53 .053
325 .0017 44 .044
400 .0015 37 .037
550 .0009 25 .025

Because of perlite's outstanding insulating characteristics and light weight, it is widely used as a loose-fill insulation in masonry construction. In this application, free-flowing perlite loose-fill masonry insulation is poured into the cavities of concrete block where it completely fills all cores, crevices, mortar areas and ear holes. In addition to providing thermal insulation, perlite enhances fire ratings, reduces noise transmission and it is rot, vermin and termite resistant. Perlite is also ideal for insulating low temperature and cryogenic vessels. When perlite is used as an aggregate in concrete, a lightweight, fire resistant, insulating concrete is produced that is ideal for roof decks and other applications. Perlite can also be used as an aggregate in Portland cement and gypsum plasters for exterior applications and for the fire protection of beams and columns. Other construction applications include under-floor insulation, chimney linings, paint texturing, gypsum boards, ceiling tiles, and roof insulation boards.

Horticultural Applications

In horticultural applications, perlite is used throughout the world as a component of soilless growing mixes where it provides aeration and optimum moisture retention for superior plant growth. For rooting cuttings, 100% perlite is used. Studies have shown that outstanding yields are achieved with perlite hydroponic systems. Other benefits of horticultural perlite are its neutral pH and the fact that it is sterile and weed-free. In addition, its light weight makes it ideal for use in container growing. Other horticultural applications for perlite are as a carrier for fertilizer, herbicides and pesticides and for pelletizing seed. Horticultural perlite is as useful to the home gardener as it is to the commercial grower. It is used with equal success in greenhouse growing, landscaping applications and in the home in house plants.

Industrial Applications

Industrial applications for perlite are the most diverse, ranging from high performance fillers for plastics to cements for petroleum, water and geothermal wells. Other applications include its use as a filter media for pharmaceuticals, food products, chemicals and water for municipal systems and swimming pools.

Additional applications include its use as an abrasive in soaps, cleaners, and polishes; and a variety of foundry applications utilizing perlite's insulating properties and high heat resistance. This same heat resistant property is taken advantage of when perlite is used in the manufacture of refractory bricks, mortars, and pipe insulation.