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Encyclopedia > Pumice
Specimen of highly porous pumice from Teide volcano on Tenerife, Canary Islands. Density of specimen approx 0.25 g/cm³. Scale is in cm.
Specimen of highly porous pumice from Teide volcano on Tenerife, Canary Islands. Density of specimen approx 0.25 g/cm³. Scale is in cm.

Pumice is a textural term for a volcanic rock that is a solidified foam composed of highly microvesicular glass pyroclastic with very thin, translucent bubble walls extrusive igneous rock. It is commonly, but not exclusively of silicic or felsic to intermediate in composition (e.g. rhyolitic, dacitic, andesite, pantellerite, phonolite, trachyte), but occurrences of basaltic and other compositions are known. Pumice is commonly pale in color, ranging from white, cream or grey, but can be green brown or black. It forms when gases exsolving from viscous magma nucleate bubbles which cannot readily decouple from the viscous magma prior to chilling to glass. Pumice is a common product of explosive eruptions (plinian and ignimbrite-forming) and commonly forms zones in upper parts of silicic lavas. Pumice has an average porosity of 90%, and initially floats on water. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Teide (Mount Teide or Pico del Teide) is a volcano and mountain on Tenerife, Canary Islands (28. ... Flag of Tenerife Tenerife in the Canary Islands chain. ... Anthem: Arrorró Capital Las Palmas de Gran Canaria and Santa Cruz de Tenerife Official language(s) Spanish Area  â€“ Total  â€“ % of Spain Ranked 13th  7,447 km²  1. ... BIC pen cap, about 1 gram. ... A cubic centimetre (cm3) is an SI derived unit of volume, equal to the volume of a cube with side length of 1 centi metre. ... This article is about the unit of length. ... Pyroclastic rocks are formed from lavas which are ejected into the air, as occur in pyroclastic flows or Plinian eruptions. ... Extrusive refers to the mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently into the atmosphere to fall back as pyroclastics or tuff. ... Volcanic rock on North America Plutonic rock on North America Igneous rocks (etymology from latin ignis, fire) are rocks formed by solidification of cooled magma (molten rock), with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. ... Porosity is a measure of the void spaces in a material, and is measured as a fraction, between 0–1, or as a percentage between 0–100%. The term porosity is used in multiple fields including manufacturing, earth sciences and construction. ...


Scoria differs from pumice in being denser, with larger vesicles and thicker vesicle walls; it sinks rapidly. The difference is the result of the lower viscosity of the magma that formed scoria. When larger amounts of gas are present, the result is a finer-grained variety of pumice known as pumicite. Pumice is considered a glass because it has no crystal 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 Pacific Ocean for up to 20 years, with tree trunks floating among them.[1] In fact, pumice rafts disperse and support several marine species.[2] In 1979, 1984 and 2006, underwater volcanic eruptions near Tonga created large pumice rafts, some as large as 30 km that floated hundreds of miles to Fiji. [3] Scoria Scoria is a textural term for macrovesicular volcanic rock ejecta. ... This article is about the material. ... Enargite crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... For the 1969 film about the Krakatoa eruption, see Krakatoa, East of Java. ... Vavau is an island chain of one large island and 40 smaller ones. ... Pumice rafts are floating rafts of stone occasionally created by ocean-based volcanic activity. ... “km” redirects here. ...

Pumice has a very low density.
Pumice has a very low density.

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 vapour pressure during eruption. Image File history File linksMetadata No higher resolution available. ... Image File history File linksMetadata No higher resolution available. ... The vapor pressure is the pressure (if the vapor is mixed with other gases, the partial pressure) of a vapor. ...

Contents

Uses

Pumice is widely used to make lightweight concrete or insulative low-density 'breeze-block' type bricks. When used as an additive for cement, a fine-grained version of pumice called pozzolan 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. This article is about the construction material. ... For other uses, see Cement (disambiguation). ... Pozzolana is a fine sandy volcanic ash, originally discovered and dug at Pozzuoli in the region around Vesuvius, but later at a number of other sites. ... This article or section does not adequately cite its references or sources. ... This article is about the construction material. ... Ancient Rome was a civilization that grew from a small agricultural community founded on the Italian Peninsula circa the 9th century BC to a massive empire straddling the Mediterranean Sea. ...


It is also used as an abrasive, especially in polishes, cosmetics exfoliants, and for stone-washed jeans. "Pumice stones" are often used in salons during the pedicure process to remove dry and excess skin from the bottom of the foot as well as calluses. Finely ground pumice is added to some toothpastes and heavy-duty hand cleaners as a mild abrasive. Perhaps the most famous product advertised to contain pumice is Lava soap. It is a heavy-duty hand soap, sold in both bar and liquid form, for mechanics and others who get very dirty hands. An abrasive is a material, often a mineral, that is used to shape or finish (see metal polishing and wood finishing) a workpiece through rubbing which leads to part of the workpiece being worn away. ... “Make-up” redirects here. ... It has been suggested that hair salon be merged into this article or section. ... Pedicure A pedicure is a way to improve the appearance of the feet, and their nails. ... Lava, commonly known as black soap, is a heavy-duty hand cleaner made by WD-40, first produced in 1893. ...


See also

Top stone is obsidian, below that is pumice and in lower right hand is rhyolite (light color) Obsidian is a type of naturally occurring glass, produced from volcanoes when the right kind of lava cools rapidly, e. ...

References

  1. ^ DeVantier, L.M. (September 1992). "Rafting of tropical marine organisms on buoyant coralla". Mar. Ecol. Prog. Ser 86: 301-302. Retrieved on 2007-07-14. “"trunks and pumice that washed ashore at (Keeling) Atoll in the early 1900's had been drifting for some 20 years, since the eruption of Krakatoa 1000 km to the northeast in 1883 (Wood-Jones 1912)."” 
  2. ^ Bryan, S.E.; A. Cook, J.P. Evans, P.W. Colls, M.G. Wells, M.G. Lawrence, J.S. Jell, A. Greig, R. Leslie (2004). "Pumice rafting and faunal dispersion during 2001–2002 in the Southwest Pacific: record of a dacitic submarine explosive eruption from Tonga". Earth and Planetary Science Letters 227: 135–154. Retrieved on 2007-07-14. “"The abundance and variety of fouling taxa, coupled with the long dispersal trajectory (>3500 km) and period of pumice floatation (≥1 year), confirm the importance of sea-rafted pumice as a long-distance dispersal mechanism for marine organisms"” 
  3. ^ "New Island and Pumice Raft in the Tongas", NASA Earth Observatory, 2006. 

Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 195th day of the year (196th in leap years) in the Gregorian calendar. ... Frederic Wood Jones (23 January 1879 – 29 September 1954) was a British observational naturalist, embryologist, anatomist and anthropologist. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 195th day of the year (196th in leap years) in the Gregorian calendar. ... NASA Earth Observatory is an online publication of NASA where the public can access satellite imagery and scientific information about our planet for free. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ...

External links

  • NSW to become the pumiced land Retrieved 2007-01-28.

  Results from FactBites:
 
Pumice - Wikipedia, the free encyclopedia (245 words)
Pumice is a light, porous type of pyroclastic igneous rock.
Pumice varies in density according to the thickness of the solid material between the bubbles; many samples float in water.
When used as an additive for cement, a fine-grained version of pumice called pozzolan is mixed with lime to form a light-weight, smooth, plaster-like concrete.
  More results at FactBites »

 
 

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