areas of land in Almeria, southern Spain, are covered
with greenhouse and polytunnels growing fruit and
vegetables using perlite-based hydroponic systems. ANE,
via Wikimedia Commons.
With niche applications and supply controlled by just a
handful of producers, perlite and vermiculite appear a world
away from the highly liquid mineral commodities typically used
to gauge economic confidence.
But demand for these products is closely tied to some of the
world’s most GDP-sensitive markets, including
construction and crop production.
According to Chuck Vogelsang, technical consultant to the
US-based Perlite Institute, perlite usage in particular is
largely dictated by the strength of the economy.
"Perlite is used all over the world and most of it goes into
the construction sector, so demand tends to be driven by the
wider economy. A pickup in economic growth tends to lead to a
rise in demand for perlite," he told IM.
Vogelsang cites the growth of Middle Eastern cities, which
expanded rapidly on oil revenues in the 2000s, as an example of
an economic event which caused typically stable perlite
consumption to spike. During its various construction booms,
the most notable of which lasted from around 2002 to 2008,
Dubai saw huge surges in demand for expanded perlite for use in
lightweight cements and insulation materials.
Lightweight cements are favoured in the Middle East since
they can be supported by intricate and tremendously tall steel
frames. The extreme temperatures of Middle Eastern desert
climates also mean that insulation materials are indispensible
in buildings. Thermal-acoustic ceiling tiles, commonly used in
offices and other modern public buildings globally, can consist
of up to 50% perlite and perlite-based masonry fill products
are commonly used in both municipal and residential
According to Vogelsang, the widespread use of perlite in
construction materials began in the US around 30 years ago
and the trend quickly spread to emerging economies, many of
which have recently undergone swift urbanisation and
But unlike other minerals, where sharp increases in
consumption can push up their value due to temporary shortages,
the price of perlite remains fairly steady, since suppliers are
usually able to respond quickly to shifts in demand.
Perlite prices published by the USGS are averaged across all
grades of perlite and therefore do not accurately reflect the
varying cost of different grades of the mineral, however they
do indicate broad price trends within the industry. "From what
has been published, you can see that generically both prices
and demand have been growing," Vogelsang points out (see
|US perlite and vermiculite prices
*Prices are average values in $/tonne,
FOB mine. **Price ranges for concentrate in $/tonne,
"Capacity is fairly flexible. Turkey for example recently
invested in a whole new perlite production facility solely to
supply the Russian market, which has been consuming an
increasing amount of perlite in the last few years".
Perlite also has a diversified end use profile, meaning that
markets tend to balance each other and prevent significant
volatility in supply or prices.
Similarly, vermiculite, which is also used in construction,
benefits from having a wide range of other applications which
contribute to an overall robust but stable industry
"Vermiculite is used in a multitude of end use markets, so
when one market is flat another can be performing very well
– not all the eggs are in one basket," Richard Knight,
commercial manager at Palabora Europe, which distributes
vermiculite sourced from its own mines in South Africa, told
"That said, current vermiculite demand remains strong. In
fact, we as a company are outperforming 2015/16. The
biggest market is building and construction and I believe that
this will remain constant, but the horticulture market will
grow – especially in areas of the world which are
struggling to grow crops due to poor soil quality," he
gold: Vermiculite is used to help propagate
daffodils, one of the biggest
commercial flower crops in the UK. Paul Pierce, via
One of the best-known uses for both perlite and vermiculite
is in horticulture, which as well as ornamental plants and
shrubs also includes certain kinds of food crops, such salad
vegetables and fruits. Adding expanded perlite to
water-holding growing media like compost provides aeration,
which aids root growth. Likewise, adding vermiculite also
helps improve drainage.
Fruit and vegetable growers around the world are continually
trying to maximise yields from ever smaller areas of land and
with as little water input as possible and nutrients like
perlite have played an important role in achieving these
In Almeria, Andalucia, southern Spain, the fruit and
vegetable industry has been transformed by the use of
perlite-based hydroponic systems – growbags filled
with the plant nutrient and watered by an irrigation network
across large greenhouse and polytunnel complexes.
The main crops grown using perlite are hydroponically grown
tomatoes, bell peppers, and chillies. In hydroponic systems,
roots are grown in troughs of perlite which is dampened with a
fertiliser solution. This allows the right amount of water and
oxygen to get to the roots. This growing medium can be replaced
much more easily than soil, which tends to accumulate pests and
According to research, growing plants hydroponically
produces a heavier crop for the space used and a better quality
product. Tomatoes, for instance, are less prone to splitting
when grown hydroponically than if they are grown in soil.
Although the hydroponic revolution has brought with it
concerns about environmental degradation and even allegations
of modern slavery against the employers of migrant labourers
that tend to the crops, this soil-free growing method has
helped to make Spain the largest producer of fruit and
vegetables in Europe. According to data from Eurostat, in value
terms, Spain accounts for around 22% of all EU fruit and
vegetable production and 34% of exports, more than any other
"Southern Spain has become the vegetable basket of Europe,
largely thanks to perlite," Vogelsang claims.
As well as being a high volume consumer, the horticultural
industry is also a relatively high-value market for perlite.
According to Vogelsang, the price of horticultural grade
perlite tends to be around 50% higher than the cost of material
used in construction.
Horticultural-grade perlite is expanded or "popped" to
produce particles – or volcanic glass "bubbles"
– that are around 1,000 microns in size by heating the
mineral rapidly to temperatures of around 900°C.
Although horticulture is one of the handful of applications
where perlite competes with vermiculite, the sector
comfortably accommodates healthy market shares for both
Perlite and vermiculite are both used to improve drainage
and lighten the texture of growing media, especially compost.
While not often added to soils, they are best suited to heavy
clay soils which are prone to waterlogging. They can also help
very thin, sandy soils, as they act like a sponge to hold onto
a small amount of water.
Both perlite and vermiculite are used in horticultural
research, such as, for example, in the testing of different
During summer months, perlite is mostly used to help grow
bedding plants for gardens. Compared to grit or sharp sand,
which can also be used to improve drainage, perlite is lighter,
which reduces transport costs, and is porous, meaning it can
hold a small amount of water to keep compost moist.
The result is that delicate seedlings and cuttings are able
to establish strong roots prior to planting out.
The construction booms in Middle Eastern
cities like Dubai generated significant demand for
perlite for use in lightweight cement and insulation
materials. Leandro Neumann Ciuffo, Via
In the markets where they compete, the choice between
perlite and vermiculite is largely determined by the economic
value of the end use product. Vermiculite is typically more
expensive than perlite, meaning that perlite is preferred for
lower value applications where the respective performance
benefits of each mineral are similar.
Perlite is preferred for applications such as filter-aids,
since its use can be extended. "If you’re
filtering something like apple juice, you end up with a lot of
pulp and apple skin from the filtering which has to be disposed
of. Because perlite is inert, this waste can be used in animal
feed – which represents an important secondary market
for perlite," Vogelsang told IM.
Another advantage of using perlite is that, unlike
vermiculite, it is never contaminated with asbestos –
a problem which affected some vermiculite producers which mined
the mineral in the US’ Mid-West states, notably
Montana, towards the end of the last century.
This led to a backlash against vermiculite usage in North
America and although suppliers in other parts of the world
benefitted slightly, Palabora Europe’s Knight says
that the asbestos issue has tainted the vermiculite industry as
"Unfortunately, we never seem to shrug off the asbestos
label, due to one event in the 1990s. But Palabora
actually benefits from the issue, as we give strong guarantees
about our vermiculite to customers."
"We have very rigorous testing processes, which are actually
being used by the global industry as an example of 'best
practice’. But, we must never be complacent
about the dangers of asbestos," he adds.
As well as competing with one another in some areas, perlite
and vermiculite consumption is also coming under pressure from
the increasing popularity of alternatives.
In horticulture, both minerals can be substituted with grit
or sharp sand for lightening heavy soils. For ornamental
gardening purposes, these camouflaged alternatives are
preferable to perlite, which is shiny and white and can be
A recent competitor material to perlite in horticulture is
biochar, a type of charcoal, which has proven very effective in
developing countries in improving the moisture-holding ability
of thin, sandy soils, while adding nutrients.
The main, obvious, advantage is that charcoal can be
produced very cheaply and easily. There is a lot research into
the benefits of biochar, but results are contradictory, partly
because the product is highly variable.
In the vermiculite market, Palabora Europe has noticed the
rise in alternatives. "World vermiculite consumption has
decreased and this is mainly due to substitution and new
methods in end use markets," Knight told IM.
"Conversely, we have more commercial mines, vying for a much
smaller piece of cake.
This has created a much more competitive market, which I
believe has benefitted customers, as suppliers have had to
improve their offerings."
Knight says that suppliers like Palabora Europe, which are
currently leaders in the vermiculite industry, cannot afford to
take their foot of the quality control pedal if they are to
hold on to market share, but some factors are more difficult to
manage than quality.
"For us logistics plays a huge role and our supply chain is
constantly being reviewed" he notes, hinting that costs have
to be squeezed wherever possible to ensure price
Both perlite and vermiculite are used to produce speciality
products tailored for specific end uses. But according to
Vogelsang, in the perlite sector, research and development
(R&D) is not a market driver. Prohibitive freight costs
mean that consumption of expanded perlite tends to be local to
the source and there is little incentive to invest in expensive
R&D for products that will not reach mass markets.
In the perlite ore market, raw ores are traded over long
distances to buyers which then convert them into products
– a model which similarly fails to foster
Knight is more optimistic about the scope for R&D in the
vermiculite industry. "Vermiculite is a technical product and
customers require high exfoliation levels and to a homogenous
product, so quality is very important."
"Whenever I speak to people about vermiculite, there seems
to very little known about its huge potential in many different
areas. Is that the fault of the vermiculite miners who
have not educated the end use market, or the exfoliators
keeping their niche markets to themselves? Whatever the blocker
is, vermiculite still has some very valuable uses which could
be realised if more research and development was carried
Knight sees the construction industry as a prime target for
innovation, saying that vermiculite-based materials could be
exploited to help make new buildings greener, in terms of
carbon footprint and energy efficiency.
"We at Palabora Europe are very keen to work with
universities, academic bodies to discover or dig deeper into
the attributes of this very specialised mineral, which covers
so many end uses," he adds.
Vermiculite in commercial flower
Vermiculite has a minor use in propagating Narcissus, or
daffodils, as well as tulips, and snowdrops grown
commercially for sale as cut flowers or to gardeners for
In a process called twin-scaling, bulbs are cut into pieces
and incubated in moist vermiculite, where they develop small
bulbs that can be grown on. This is slightly quicker than
waiting for bulbs to multiply naturally.
Research conducted at the UK’s University of
Warwick’s Crop Centre is attempting to find
alternatives to vermiculite that are less complicated and messy
to use, such as on damp paper or mineral wool.
So far, however, this research has not yielded a viable
alternative to vermiculite.