
Pumice (), called pumicite in its powdered or dust form, is a
volcanic rock
Volcanic rocks (often shortened to volcanics in scientific contexts) are rocks formed from lava erupted from a volcano. Like all rock types, the concept of volcanic rock is artificial, and in nature volcanic rocks grade into hypabyssal and me ...
that consists of extremely
vesicular rough-textured
volcanic glass, which may or may not contain crystals. It is typically light-colored.
Scoria is another vesicular volcanic rock that differs from pumice in having larger vesicles, thicker vesicle walls, and being dark colored and denser.
[Jackson, J.A., J. Mehl, and K. Neuendorf (2005) ''Glossary of Geology'' American Geological Institute, Alexandria, Virginia. 800 pp. ][McPhie, J., M. Doyle, and R. Allen (1993) ''Volcanic Textures A guide to the interpretation of textures in volcanic rocks'' Centre for Ore Deposit and Exploration Studies, University of Tasmania, Hobart, Tasmania..198 pp. ]
Pumice is created when super-heated, highly pressurized rock is rapidly ejected from a
volcano
A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.
On Earth, volcanoes are most oft ...
. The unusual foamy configuration of pumice happens because of simultaneous rapid cooling and rapid depressurization. The depressurization creates bubbles by lowering the
solubility
In chemistry, solubility is the ability of a chemical substance, substance, the solute, to form a solution (chemistry), solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form su ...
of gases (including
water
Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...
and
CO2) that are dissolved in the lava, causing the gases to rapidly
exsolve (like the bubbles of CO
2 that appear when a carbonated drink is opened). The simultaneous cooling and depressurization freeze the bubbles in a
matrix. Eruptions under water are rapidly cooled and the
large volume of pumice created can be a shipping hazard for cargo ships.
Properties
Pumice is composed of highly
microvesicular glass
pyroclastic with very thin, translucent bubble walls of
extrusive igneous rock
Igneous rock ( ), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava.
The magma can be derived from partial ...
. It is commonly but not exclusively of
silicic or
felsic to intermediate in composition (e.g.,
rhyolitic,
dacitic,
andesite
Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomina ...
,
pantellerite,
phonolite,
trachyte), but
basaltic
Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron ( mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90% ...
and other compositions are known. Pumice is commonly pale in color, ranging from white, cream, blue or grey, to green-brown or black. It forms when
volcanic gas
Volcanic gases are gases given off by active (or, at times, by dormant) volcanoes. These include gases trapped in cavities (Vesicular texture, vesicles) in volcanic rocks, dissolved or dissociated gases in magma and lava, or gases emanating from ...
es exsolving from viscous
magma
Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma (sometimes colloquially but incorrectly referred to as ''lava'') is found beneath the surface of the Earth, and evidence of magmatism has also ...
form bubbles that remain within the viscous magma as it cools to glass. Pumice is a common product of explosive eruptions (
plinian and
ignimbrite
Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surrou ...
-forming) and commonly forms zones in upper parts of silicic
lava
Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...
s. Pumice has a
porosity of 64–85% by volume and it floats on water, possibly for years, until it eventually becomes waterlogged and sinks.
Scoria differs from pumice in being denser. With larger vesicles and thicker vesicle walls, scoria sinks rapidly. The difference is the result of the lower viscosity of the magma that forms scoria. When larger amounts of gas are present, the result is a finer-grained variety of pumice known as pumicite. Pumicite consists of particles less than in size. Pumice is considered a
volcanic glass because it has no
crystal
A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...
structure. Pumice varies in density according to the thickness of the solid material between the bubbles; many samples float in water. After the explosion of
Krakatoa,
rafts of pumice drifted through the Indian Ocean for up to 20 years, with tree trunks floating among them. In fact, pumice rafts disperse and support several marine species. In 1979, 1984 and 2006, underwater volcanic eruptions near
Tonga
Tonga, officially the Kingdom of Tonga, is an island country in Polynesia, part of Oceania. The country has 171 islands, of which 45 are inhabited. Its total surface area is about , scattered over in the southern Pacific Ocean. accordin ...
created large pumice rafts that floated hundreds of kilometres to
Fiji
Fiji, officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consists of an archipelago of more than 330 islands—of which about ...
.
There are two main forms of vesicles. Most pumice contains tubular microvesicles that can impart a silky or fibrous fabric. The elongation of the microvesicles occurs due to
ductile elongation in the volcanic conduit or, in the case of pumiceous lavas, during flow. The other form of vesicles are subspherical to spherical and result from high
vapor pressure
Vapor pressure or equilibrium vapor pressure is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. The equilibrium vapor pressure is an indicat ...
during an eruption. Reticulite is a type of basaltic pumice formed in very high
lava fountains. It has an extremely low density and is composed of a network of volcanic glass formed when the vesicles have almost completely coalesced.
File: Pumice stone detail444.jpg, Illustrates the porous nature in detail.
File: BishopTuff.jpg, Rocks from the Bishop tuff
The Bishop Tuff is a welded tuff which formed 764,800 ± 600 years ago as a rhyolite, rhyolitic pyroclastic flow during the approximately six-day eruption that formed the Long Valley Caldera. Large outcrops of the tuff are located in Inyo County, ...
, uncompressed with pumice on left; compressed with fiamme on right.
File:Akrotiri Santorini-Volcano pumice-layers Aegean-Sea.jpg, Two layers of pumice, first major phase of the Late-Bronze-Age volcano eruption (~ 1500 BC), southern part of the caldera
A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...
island Thera/ Santorini. The lower layer is finer, almost white and without intrusions.
Etymology
Pumice is an igneous rock with a foamy appearance. The name is derived from the Latin word ''pumex'' (meaning "pumice")
which is related to the Latin word ''spuma'' meaning "foam".
In former times, pumice was called "Spuma Maris", meaning "froth of the sea" in Latin because the frothy material was thought to be hardened sea foam. Around 80 B.C., it was called "lapis spongiae" in Latin for its vesicular properties. Many Greek scholars decided there were different sources of pumice, one of which was in the sea coral category.
Distribution
Pumice can be found all around the globe deriving from continental volcanic occurrences and submarine volcanic occurrences. Floating stones can also be distributed by ocean currents.
As described earlier pumice is produced by the eruption of explosive volcanoes under certain conditions, therefore, natural sources occur in volcanically active regions. Pumice is mined and transported from these regions. In 2011, Italy and Turkey led pumice mining production at 4 and 3 million tons respectively; other large producers at or exceeding a million tonnes were Greece, Iran, Chile, and Syria. Total world pumice production in 2011 was estimated at 17 million tonnes.
Asia
There are large reserves of pumice in Asian countries including Afghanistan, Indonesia, Japan, Syria, Iran, and eastern Russia. Considerable amounts of pumice can be found at the
Kamchatka Peninsula on the eastern flank of Russia. This area contains 19 active volcanoes and it lies in close proximity with the
Pacific volcanic belt. Asia is also the site of the second-most dangerous volcanic eruption in the 20th century,
Mount Pinatubo
Mount Pinatubo is an active stratovolcano in the Zambales Mountains in Luzon in the Philippines. Located on the tripoint of Zambales, Tarlac and Pampanga provinces, most people were unaware of its eruptive history before the pre-eruption volc ...
, which
erupted on June 12, 1991 in the
Philippines
The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...
. Ash and pumice
lapilli were distributed over a mile around the volcano. These ejections filled trenches that once reached 660 feet deep. So much magma was displaced from the vent that the volcano became a depression on the surface of the Earth.
Another well-known volcano that produces pumice is
Krakatoa. An eruption in 1883 ejected so much pumice that kilometers of sea were covered in floating pumice and in some areas rose 1.5 meters above sea level.
Europe
Europe is the largest producer of pumice with deposits in Italy, Turkey, Greece, Hungary, Iceland, and Germany. Italy is the largest producer of pumice because of its numerous eruptive volcanoes. On the
Aeolian Islands of Italy, the island of
Lipari is entirely made up of volcanic rock, including pumice. Large amounts of igneous rock on Lipari are due to the numerous extended periods of volcanic activity from the Late
Pleistocene
The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
(
Tyrrhenian) to the Holocene.
North America
Pumice can be found all across North America including on the
Caribbean Islands. In the United States, pumice is mined in
Nevada
Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...
,
Oregon
Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...
,
Idaho
Idaho ( ) is a landlocked U.S. state, state in the Pacific Northwest and Mountain states, Mountain West subregions of the Western United States. It borders Montana and Wyoming to the east, Nevada and Utah to the south, and Washington (state), ...
,
Arizona
Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...
,
California
California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
,
New Mexico
New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...
and
Kansas
Kansas ( ) is a landlocked U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the west. Kansas is named a ...
. U.S. production of pumice and pumicite in 2011 was estimated at 380,000 tonnes, valued at $7.7 million with approximately 46% coming from Nevada and Oregon.
Idaho is also known as a large producer of pumice because of the quality and brightness of the rock found in local reserves. One of the most famous volcanoes was
Mount Mazama that erupted 7,700 years ago in Oregon and deposited 300 feet of pumice and ash around the vent. The large amount of magma that was erupted caused the structure to collapse, forming a caldera now known as
Crater Lake.
South America
Chile
Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...
is one of the leading producers of pumice in the world. The
Puyehue-Cordón Caulle are two coalesced volcanoes in the
Andes
The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...
mountains that ejected ash and pumice across Chile and
Argentina
Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...
. A recent eruption in 2011 wreaked havoc on the region by covering all surfaces and lakes in ash and pumice.
Africa
Kenya
Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...
,
Ethiopia
Ethiopia, officially the Federal Democratic Republic of Ethiopia, is a landlocked country located in the Horn of Africa region of East Africa. It shares borders with Eritrea to the north, Djibouti to the northeast, Somalia to the east, Ken ...
and
Tanzania
Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; the Indian Ocean to the east; Mozambique and Malawi to t ...
have some deposits of pumice.
New Zealand
The
Havre Seamount
Havre Seamount is an active volcanic seamount lying within the Kermadec Islands group of New Zealand, in the south-west Pacific Ocean, on the Tonga-Kermadec Ridge. Its 2012 Kermadec Islands eruption, most recent eruption took place in July 2012 ...
volcano produced the largest-known deep ocean volcanic eruption on Earth. The volcano
erupted in July 2012 but remained unnoticed until enormous pieces of pumice were seen to be floating on the Pacific Ocean. Blankets of rock reached a thickness of 5 meters. Most of this floating pumice is deposited on the northwest coast of
New Zealand
New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...
and the
Polynesia
Polynesia ( , ) is a subregion of Oceania, made up of more than 1,000 islands scattered over the central and southern Pacific Ocean. The indigenous people who inhabit the islands of Polynesia are called Polynesians. They have many things in ...
islands.
Mining
The
mining
Mining is the Resource extraction, extraction of valuable geological materials and minerals from the surface of the Earth. Mining is required to obtain most materials that cannot be grown through agriculture, agricultural processes, or feasib ...
of pumice is an environmentally friendly process compared with other mining methods because the igneous rock is deposited on the surface of the earth in loose aggregate form. The material is mined by open-pit methods. Soils are removed by machinery in order to obtain more pure quality pumice. Scalping screens are used to filter impure surficial pumice of organic soils and unwanted rocks. Blasting is not necessary because the material is unconsolidated, therefore only simple machinery is used such as bulldozers and power shovels. Different sizes of pumice are needed for specific uses therefore crushers are used to achieve desired grades ranging from lump, coarse, intermediate, fine, and extra fine.
Use in volcanology
The detailed study of pumice, both in its areal and
stratigraphic distribution, as well as in its internal structure and chemistry, plays an important role in
volcanology
Volcanology (also spelled vulcanology) is the study of volcanoes, lava, magma and related geology, geological, geophysical and geochemistry, geochemical phenomena (volcanism). The term ''volcanology'' is derived from the Latin language, Latin ...
and the broader
Earth science
Earth science or geoscience includes all fields of natural science related to the planet Earth. This is a branch of science dealing with the physical, chemical, and biological complex constitutions and synergistic linkages of Earth's four spheres ...
s. Several different types of internal structures and components in pumice exist at different scales and each allows
volcanologists to decode different types of information about the
eruption that formed the pumice. Beginning at the largest scale, pumice often contains abundant
vesicles—void spaces left behind by bubbles that developed in the material while it was still molten, as a result of its formation by
explosive volcanism with abundant
gas. The abundance and morphology of vesicles in pumice offer direct evidence of
volatile exsolution and
degassing dynamics during the eruption that formed the rock. By analyzing vesicle size distributions, connectivity, and spatial arrangements, volcanologists can infer the history, style, and
flow dynamics of a particular eruption. For instance, a high density of isolated vesicles may indicate rapid
decompression and limited bubble coalescence, characteristic of more explosive eruptions, while interconnected vesicle networks could suggest more efficient gas escape and a more
effusive eruptive style.
While vesicles in pumice constitute their own utility to volcano science, the
glassy matrix or groundmass that makes up the larger part of the solid component in pumice can also provide a wealth of information for study. This matrix material consists of abundant, microscopic fragments of glass—quenched melt—representing the final bulk composition of the
magma
Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma (sometimes colloquially but incorrectly referred to as ''lava'') is found beneath the surface of the Earth, and evidence of magmatism has also ...
at the moment of eruption and
fragmentation, and as such can be a kind of
geochemical
Geochemistry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans. The realm of geochemistry extends beyond the Earth, encompassing the ...
fingerprint, allowing researchers to identify the source of an eruption and reconstruct the
evolution
Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...
of its magma. Additionally, the distribution and composition of
crystals and
lithic fragments embedded in the pumice matrix provide a window into the history of magmatic processes in the subsurface. Careful analysis of the mineral assemblages in pumice can be used to determine temperature, pressure, and volatile content in the
magma chamber
A magma chamber is a large pool of liquid rock beneath the surface of the Earth. The molten rock, or magma, in such a chamber is less dense than the surrounding country rock, which produces buoyant forces on the magma that tend to drive it u ...
and greater
transcrustal volcanic plumbing system. Volcanologists can examine the distribution of crystal sizes in pumice and use
diffusion chronometry to examine compositional zoning in individual crystals in order to gain an understanding into the timescales involved in a single eruption—the
residence time of the crystal in the magma chamber before it was erupted.
Lithic fragments, derived from the walls of volcanic conduits or from the
country rock, offer additional evidence in the way of eruptive processes and
wall-rock assimilation.
Finally, at the smallest scale,
melt inclusions trapped within growing crystals in the melt and preserved in the erupted pumice product serve as time capsules of magmatic conditions prior to and during eruption. These inclusions may contain a variety of materials ranging from
silicate
A silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is also used ...
melt, volatiles such as H
2O and CO
2, and less frequently,
sulfide
Sulfide (also sulphide in British English) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to large families o ...
s and/or
halogens, preserving information about the pre-eruptive volatile budget and
redox state of the magma chamber. Analysis of the shapes of melt inclusions—namely, the degree to which originally bubble-shaped melt inclusions have become faceted over time—can be used as an additional
chronometer and indication of magma residence time and repose of the volcanic system. Through detailed analysis of melt inclusion chemistry and volatile contents, volcanologists can reconstruct the conditions of a volcanic system in the subsurface prior to eruption, providing information about the eruptive process that not only increases understanding of volcanic eruptions as a subject of scientific study, but also helps scientists and policymakers in the area of planning for
volcanic hazards. As such, pumice is not merely a product of explosive volcanism, but a vital archive of eruptive processes and magmatic evolution.
Other uses
Pumice is a very lightweight, porous and abrasive material and it has been used for centuries in the construction and beauty industry as well as in early medicine. It is also used as an
abrasive, especially in
polishes, pencil
erasers, and the production of
stone-washed jeans. Pumice was also used in the early book-making industry to prepare parchment paper and leather bindings. There is high demand for pumice, particularly for water filtration, chemical spill containment, cement manufacturing,
horticulture and increasingly for the pet industry. The mining of pumice in environmentally sensitive areas has been under more scrutiny after such an operation was stopped in the U.S. state of Oregon, at Rock Mesa in the southern part of the
Three Sisters Wilderness.
Early medicine
Pumice has been used in the medicinal industry for more than 2000 years. Ancient Chinese medicine used ground pumice along with ground
mica and fossilized bones added to teas to calm the spirit. This tea was used to treat dizziness, nausea, insomnia, and anxiety disorders. Ingestion of these pulverized rocks was believed to be able to soften nodules and was later used with other herbal ingredients to treat gallbladder cancer and urinary difficulties. In Western medicine, beginning in the early 18th century, pumice ground into a sugar consistency mixed with other ingredients was used to attempt to treat ulcers mostly on the skin and cornea. Concoctions such as these were also used to help wounds scar in a supposedly healthier manner. In approximately 1680 it was noted by an English naturalist that pumice powder was used to promote sneezing.
Personal care

Pumice has been used as a material in personal care for thousands of years. It is an abrasive material that can be used in powdered form or as a stone to remove unwanted hair or skin. In ancient
Egypt
Egypt ( , ), officially the Arab Republic of Egypt, is a country spanning the Northeast Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via the Sinai Peninsula. It is bordered by the Mediterranean Sea to northe ...
, it was common to remove all hair on the body to control
lice and as a form of ritual purification, using creams, razors, and pumice stones. Pumice in powdered form was an ingredient in toothpastes in ancient Rome. Nail care was very important in ancient China; nails were kept groomed with pumice stones, and pumice stones were also used to remove calluses.
It was discovered in a Roman poem that pumice was used to remove dead skin as far back as 100 BC, and likely before then. It has been used throughout many eras since then, including the
Victorian Era
In the history of the United Kingdom and the British Empire, the Victorian era was the reign of Queen Victoria, from 20 June 1837 until her death on 22 January 1901. Slightly different definitions are sometimes used. The era followed the ...
. Today, many of these techniques are still used; pumice is widely used as a skin
exfoliant. Even though hair removal techniques have evolved over the centuries, abrasive material like pumice stones is also still used. "Pumice stones" are often used in beauty salons during the
pedicure process to remove dry and excess skin from the bottom of the foot as well as
calluses.
Finely ground pumice has been added to some
toothpaste
Toothpaste is a paste or gel dentifrice that is used with a toothbrush to clean and maintain the aesthetics of Human tooth, teeth. Toothpaste is used to promote oral hygiene: it is an abrasive that aids in removing dental plaque and food from th ...
s as a polish, similar to Roman use, and easily removes
dental plaque build-up. Such toothpaste is too abrasive for daily use. Pumice is also added to heavy-duty hand cleaners (such as
lava soap) as a mild abrasive. Some brands of
chinchilla dust bath are formulated with powdered pumice. Old beauty techniques using pumice are still employed today but newer substitutes are easier to obtain.
Cleaning

Pumice stone, sometimes attached to a handle, is an effective scrubbing tool for removal of limescale, rust, hard water rings, and other stains on porcelain fixtures in households (e.g., bathrooms). It is a quick method compared to alternatives like chemicals or
vinegar and
baking soda or
borax.
Horticulture
Good soil requires sufficient water and nutrient loading as well as little compaction to allow easy exchange of gases. The roots of plants require continuous transportation of
carbon dioxide
Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
and
oxygen
Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...
to and from the surface. Pumice improves the quality of soil because of its porous properties; water and gases can be transported easily through the pores and nutrients can be stored in the microscopic holes. Pumice rock fragments are inorganic therefore no decomposition and little compaction occur.
Another benefit of this inorganic rock is that it does not attract or host
fungi
A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
or
insects
Insects (from Latin ') are hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed ...
. As drainage is very important in horticulture, with the presence of pumice
tillage
Tillage is the agriculture, agricultural preparation of soil by mechanical wikt:agitation#Noun, agitation of various types, such as digging, stirring, and overturning. Examples of manual labour, human-powered tilling methods using hand tools inc ...
is much easier. Pumice usage also creates ideal conditions for growing plants like
cacti and
succulents as it increases the water retention in sandy soils and reduces the density of
clayey soils to allow more transportation of gases and water. The addition of pumice to soil improves and increases vegetative cover as the roots of plants make slopes more stable therefore it helps reduce
erosion
Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...
. It is often used on roadsides and ditches and commonly used in turf and golf courses to maintain grass cover and flatness that can degrade due to large amounts of traffic and compaction. Chemically pumice is
pH neutral, neither
acidic nor
alkaline
In chemistry, an alkali (; from the Arabic word , ) is a basic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a soluble base has a pH greater than 7.0. The ...
. In 2011, 16% of pumice mined in the United States was used for horticultural purposes.
Pumice contributes to soil fertility in areas where it is naturally present in the soil due to volcanic activity. For example, in the
Jemez Mountains of New Mexico, the
Ancestral Puebloans settled on "pumice patches" of the
El Cajete Pumice which likely retained a greater amount of moisture and was ideal for farming.
Construction
Pumice is widely used to make lightweight
concrete
Concrete is a composite material composed of aggregate bound together with a fluid cement that cures to a solid over time. It is the second-most-used substance (after water), the most–widely used building material, and the most-manufactur ...
and
insulative low-density
cinder blocks. The air-filled vesicles in this porous rock serve as a good insulator.
A fine-grained version of pumice called
pozzolan is used as an additive in cement and is mixed with
lime to form a light-weight, smooth, plaster-like concrete. This form of concrete was used as far back as
Roman times. Roman engineers utilized it to build the huge dome of the
Pantheon with increasing amounts of pumice added to concrete for higher elevations of the structure. It was also commonly used as a construction material for many
aqueducts.
One of the main uses of pumice currently in the United States is manufacturing concrete. This rock has been used in concrete mixtures for thousands of years and continues to be used in producing concrete, especially in regions close to where this volcanic material is deposited.
New studies prove a broader application of pumice powder in the concrete industry. Pumice can act as a cementitious material in concrete and researchers have shown that concrete made with up to 50% pumice powder can significantly improve durability yet reduce greenhouse gas emissions and fossil fuel consumption.
[
]
See also
*
References
External links
University of Oxford image of pumice.
Retrieved 2010-09-27.
Analytical identification of single source pumice from Greek shores and ancient sites in the Levant
On the occurrence of a pumice-rich layer in Holocene deposits of western Peloponnesus, Ionian Sea, Greece. A geomorphological and geochemical approach.
- White papers and technical info of pumice.
{{Authority control
Abrasives
Igneous rocks
Industrial minerals
Personal hygiene products
Skin care
Vitreous rocks
Volcanic rocks
Volcanology