Industrial Perlites - Milled


Ryolex-Milled is our brand of expanded perlite we refer to as macro shards. Using milled perlite has unique advantages as an ultra-fine filler. The process starts by expanding siliceous volcanic rock and then milling it down under strict quality control conditions to create a surface area that acts as jagged interlocking structures. The main difference milled perlite has from non-milled is that its increased surface area acts as a “carrier” for other types of chemically designed additives and coating.

We make Ryolex in both milled and non-milled forms.


The many applications for milled Ryolex include:

  • Silicone rubber
  • Synthetic rubbers
  • Thermoplastic resins, including Polyethylene and PVC
  • Paint
  • Coating
  • Polishes


This 3-dimensional structure helps reduce shrinkage upon drying or curing, maintaining the physical dimensions of the host material. This also allows for companies to apply their own chemical binding solutions to attract and remove what they wish. The standard size for milled perlite shards is below 300 microns (50 mesh). The density usually ranges from 5 to 15 pounds per cubic foot (80-240 kg/m3).

Perlite Benefits

  • Very lightweight
  • Reinforcing structures
  • Fine particle size
  • High brightness
  • Mild abrasiveness
  • Low volumetric cost
  • Availability

Chemical Analysis

SiO2Silicon Dioxide73%

Al2O3Aluminum Oxide17%

K20Potassium Oxide5%

Na20Sodium Oxide3%

CaOCalcium Oxide1%

Trace Elements1%

Physical Properties

Hydroscopic Moisture 0%

Surface pH 6.5-7.5

Color White

Fusion Point (°F) 2300

Fusion Point (°C) 1260

Trace Elements

Manganese < 0.3%
Sulfur < 0.2%
Titanium < 0.1%
Barium < 0.1%
Gallium < 0.05%
Boron < 0.01%
Chromium < 0.0075%
Zirconium < 0.003%
Molybdenum < 0.002%
Nickel < 0.002%
Copper < 0.0015%
Lead < 0.001%*
Arsenic < 0.001%
Chlorine < 0.0005%

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.

*By Food Chemicals Codex Method