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Properties

• Illustrates the porous nature in detail.
• Rocks from the Bishop tuff, uncompressed with pumice on left; compressed with fiamme on right.
• A 15-centimeter (5.9 in) piece of pumice supported by a rolled-up U.S. 20-dollar bill demonstrates its very low density.

Etymology

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 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.

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. 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 (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, 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. 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 is one of the leading producers of pumice in the world. 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.

Africa

Kenya, Ethiopia and Tanzania have some deposits of pumice.

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. 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.

Uses

See also

• Pumice raft – Floating mass of pumice in the ocean

References

1. ^ "What is Pumice?". WorldAtlas. 28 July 2017.
2. ^ Crangle, Robert D. Jr. (January 2012). "Pumice and pumicite - USGS Mineral Resources Program" (PDF). United States Geological Survey. Retrieved 25 November 2018.
3. ^ "Pumice: Igneous Rock - Pictures, Definition & More". geology.com.
4. "Pumice | volcanic glass". Encyclopedia Britannica.
5. 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.
6. "What is Pumice: Origin of Pumice: From Stone to Refined Pumice Powder". hesspumice.com.
7. Bolen, Wallace. "Pumice and Pumicite" (PDF).
8. Taylor, Alan. "Volcanic Ash and Pumice From Puyehue - The Atlantic". www.theatlantic.com.
9. "Havre - the world's largest deep ocean volcanic eruption". Radio New Zealand. 12 June 2018.
10. Geroge, S. "Pumice Mining and Environmental Concerns in New Mexico" (PDF).

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.
• Hess Pumice - White papers and technical info of pumice.

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• Vitreous rocks
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