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Pumice

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Specimen of highly porous pumice from Teide volcano on Tenerife, Canary Islands. Density of specimen approximately 0.25 g/cm3; scale in centimeters.
Kutkhiny Baty, a pumice rock formation outcrop located 4 km from the source of the Ozernaya River (Lake Kurile), near the southern tip of the Kamchatka Peninsula, Russia.

Pumice is an igneous rock with a foamy appearance. The name is derived from the Latin word pumex (meaning "pumice")[1] which is related to the Latin word spuma meaning "foam".[2] 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.[3]

Location

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.[4] 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 tonnes 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.[5]

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, which erupted on June 12, 1991 in the Philippines. 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.[6] 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.[7]

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 (Tyrrhenian) to the Holocene.[8]

North America

Pumice can be found all across North America including on the Caribbean Islands. In the United States, pumice is mined in Nevada, Oregon, Idaho, Arizona, California, New Mexico and Kansas. 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.[5] Idaho is also known as a large producer of pumice because of the quality and brightness of the rock found in local reserves.[9] 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.[6]

South America

Chile is one of the leading producers of pumice in the world.[10] The Puyehue-Cordón Caulle are two coalesced volcanoes in the Andes mountains that ejected ash and pumice across Chile and Argentina. A recent eruption in 2011 wreaked havoc on the region by covering all surfaces and lakes in ash and pumice.[11]

Africa

Kenya, Ethiopia and Tanzania have some deposits of pumice.[4]

New Zealand

The Havre Seamount 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.[12] Most of this floating pumice is deposited on the North-West coast of New Zealand and the Polynesia islands.

Mining

The mining 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.[13]

Uses

Bar of solid pumice stone

Pumice stone, sometimes attached to a handle,[14] 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 and oxygen 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 or insects. Drainage is very important in horticulture, with the presence of pumice tillage 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. 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. With regard to chemical properties pumice is pH neutral, it is not acidic or alkaline.[15] In 2011, 16% of pumice mined in the United States was used for horticultural purposes.[5]

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.[16]

Construction

Pumice is widely used to make lightweight concrete and insulative low-density cinder blocks. The air-filled vesicles in this porous rock serves as a good insulator.[6] 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.[17] 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.[18]

See also

References

  1. ^ "Pumice". Merriam-Webster.com Dictionary. Merriam-Webster. Retrieved 23 February 2022.
  2. ^ "Spume". Merriam-Webster.com Dictionary. Merriam-Webster. Retrieved 23 February 2022.
  3. ^ Duffin, Christopher J. (1 January 2012). "History of the pharmaceutical use of pumice" (PDF). Geological Society, London, Special Publications. 375: 157–169. doi:10.1144/SP375.8. S2CID 129854945.
  4. ^ a b "What is Pumice?". WorldAtlas. 28 July 2017.
  5. ^ a b c Crangle, Robert D. Jr. (January 2012). "Pumice and pumicite - USGS Mineral Resources Program" (PDF). United States Geological Survey. Retrieved 25 November 2018.
  6. ^ a b c "Pumice: Igneous Rock - Pictures, Definition & More". geology.com.
  7. ^ "Pumice | volcanic glass". Encyclopedia Britannica.
  8. ^ Liguori, V.; Sciorta, R.; Ruisi, V. (1 December 1984). "The pumice aggregates of Lipari Island (Aeolian Isles-Italy)". Bulletin of the International Association of Engineering Geology. 30: 431–434. doi:10.1007/BF02594356. S2CID 127008263.
  9. ^ "What is Pumice: Origin of Pumice: From Stone to Refined Pumice Powder". hesspumice.com.
  10. ^ Bolen, Wallace. "Pumice and Pumicite" (PDF).
  11. ^ Taylor, Alan. "Volcanic Ash and Pumice From Puyehue - The Atlantic". www.theatlantic.com.
  12. ^ "Havre - the world's largest deep ocean volcanic eruption". Radio New Zealand. 12 June 2018.
  13. ^ Geroge, S. "Pumice Mining and Environmental Concerns in New Mexico" (PDF).
  14. ^ "Amazon.com: Powerhouse Pumice Toilet Bowl Cleaning Stone with Handle (2-Pack) – Removes Stains, Limescale, Hard Water Rings, Calcium Buildup, Iron and Rust: Home & Kitchen". www.amazon.com. Retrieved 2021-05-15.
  15. ^ "Improving Soil and other Horticultural Use for Natural Pumice". hesspumice.com.
  16. ^ Gauthier, Rory; Powers, Robert; Herhahn, Cynthia; Bremer, Mike; Goff, Fraser (2007). "Dry farming El Cajete Pumice: Pueblo farming strategies in the Jemez Mountains, New Mexico" (PDF). New Mexico Geological Society Field Conference Series. 58: 469–474. Retrieved 10 January 2021.
  17. ^ Grasser, Klaus. Building with Pumice (PDF). p. 64. Retrieved 23 March 2019.
  18. ^ Askarian, Mahya; Fakhretaha Aval, Siavash; Joshaghani, Alireza (22 January 2019). "A comprehensive experimental study on the performance of pumice powder in self-compacting concrete (SCC)". Journal of Sustainable Cement-Based Materials. 7 (6): 340–356. doi:10.1080/21650373.2018.1511486. S2CID 139554392.
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