Coarse Vermiculite

Interesting Facts about Coarse Vermiculite

A unique and naturally occurring mineral, or rather group of minerals, called coarse vermiculite has proven to be quite valuable in a number of different industries, including agriculture, industry and construction.  Though many people are unaware of its many uses, it can actually be found in an unexpected number of products that are used daily.

What it is

The term vermiculite is applied to a rather large combination of silicates that bear a resemblance to mica. It is mined in various locations across the world, with some of the largest mines found in Brazil, South Africa and China.  The United States has several locations where the mineral has been harvested, as well.  Two unique features are common for vermiculite:  1) the ability to expand in a linear manner due to its layered formation, and 2) it has the ability to trap water that converts to steam when heated.  Though there are several varieties of vermiculite, the most commonly used variety is commercial vermiculite, which is made from rocks that contain large crystals of biotite and phlogopite.  These rocks decompose when exposed to weather elements, which enables moisture to enter the layers and cause a chemical reaction.  As this process advances through manufacture, common vermiculite is formed.



Once removed from the mines, the rocks are subjected to crushing and screening to diminish their size.  Dirt, debris and unnecessary rock are separated from the vermiculite until raw flakes are produced that are close to 90% pure.  The flakes are identified and graded by size either through screening or air chafing.  They are then ready for a process called “exfoliating” in which they are exposed to high degrees of heat to transpose the trapped water within the layers into steam.  This process converts the flakes into long, wormlike particles.  After cooling, these particles are ground into either fine or coarse vermiculite that will be used in a variety of different methods.


The unusual properties of vermiculite make it very useful in a number of diverse applications in various industries.  It is lightweight, non-combustible, extremely absorbent and non-reactive.  One use that most people are familiar with is using vermiculite in gardening pursuits, especially hydroponics.  The ability to hold water and nutrients into the soil where the roots can access it make it a valuable tool for soilless gardening.   Its lighter weight is beneficial for the growth of tiny seedlings, whose tender root systems can expand without struggling against compacted garden soil.  When mixed with normal gardening soil, larger sized coarse vermiculite provides soil aeration and conditioning for horticultural and agricultural use.

Many other uses are attributed to vermiculite in industries such as manufacturing and construction, as well.  High temperature insulation, a fireproofing additive, pool base material, a blast mitigate for explosives and a packing material are just a few of the numerous applications of this unique mineral.  Large particles of the mineral are shipped side by side with liquid products that have the potential for spill, as its absorbent nature will soak up the spill before causing problems. This property also makes it vital for hazardous liquids, which can then be carefully disposed of in solid form.

Unexpected uses for the mineral are as a sterile medium for incubating reptilian eggs as well as the eggs of other animals.  It is also safe for use as their habitat medium.  This same element is used in commercial hand or foot warmers along with charcoal.

It is highly unusual that one element can produce so many beneficial uses in so many different industries.  Coarse vermiculite may not be a name on every consumer’s lips, but likely is present somewhere in each person’s home or workplace in an unexpected application.