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Black sand

From Wikipedia, the free encyclopedia
Black sand on a beach in Southern Iceland
Closeup of black sand from a beach in Maui, Hawaii
Black sand beach in Waianapanapa Park, Hawaii
Black sand and icebergs on a beach in Iceland

Black sand is sand that is black in color. One type of black sand is a heavy, glossy, partly magnetic mixture of usually fine sands containing minerals such as magnetite, found as part of a placer deposit. Another type of black sand, found on beaches near a volcano, consists of tiny fragments of basalt.

While some beaches are predominantly made of black sand, even other color beaches (e.g. gold and white) can often have deposits of black sand, particularly after storms. Larger waves can sort out sand grains leaving deposits of heavy minerals visible on the surface of erosion escarpments.

Placer deposits

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Black sands and gold in sluicebox, Blue Ribbon Mine, Alaska
Magnet for separation of black sand by hand

Black sands are used by miners and prospectors to indicate the presence of a placer formation. Placer mining activities produce a concentrate that is composed mostly of black sand. Black sand concentrates often contain additional valuables, other than precious metals: rare earth elements, thorium, titanium, tungsten, zirconium and others are often fractionated during igneous processes into a common mineral-suite that becomes black sands after weathering and erosion.

Several gemstones, such as garnet, topaz, ruby, sapphire, and diamond are found in placers and in the course of placer mining, and sands of these gems are found in black sands and concentrates. Purple or ruby-colored garnet sand often forms a showy surface dressing on ocean beach placers.

An example of a non-volcanic black sand beach is at Langkawi in Malaysia.[1]

Basalt fragments

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Black sand forming when lava hits ocean. Kīlauea volcano.

When lava contacts water, it cools rapidly and shatters into sand and fragmented debris of various size. Much of the debris is small enough to be considered sand. A large lava flow entering an ocean may produce enough basalt fragments to build a new black sand beach almost overnight. The famous "black sand" beaches of Hawaii, such as Punaluʻu Beach and Kehena Beach, were created virtually instantaneously by the violent interaction between hot lava and sea water.[2] Since a black sand beach is made by a lava flow in a one time event, they tend to be rather short lived since sands do not get replenished if currents or storms wash sand into deeper water. For this reason, the state of Hawaii has made it illegal to remove black sand from its beaches. Further, a black sand beach is vulnerable to being inundated by future lava flows, as was the case for Hawaiʻi's Kaimū, usually known simply as Black Sand Beach, and Kalapana beaches.[3] An even shorter-lived black sand beach was Kamoamoa.[4] Unlike with white and green sand beaches, walking barefoot on black sand can result in burns, as the black sand absorbs more solar radiation.[5]

Beaches

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Black sand has formed beaches in places including:[6][7][8]

Europe

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Africa

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North America

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  • Canada
    • Black Beach, Lorneville, New Brunswick (near Coleson Cove Generating station, west of Saint John)
    • Salmon Cove Beach, Conception Bay, Newfoundland
  • Mexico
    • Playa Patzcuarito (Nayarit)
    • Playa La Ventanilla (Oaxaca)
  • United States

Central America

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Caribbean

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  • Grand Anse beach, Basse-Terre
  • Grenada
  • Venezuela
  • Barranquilla, Colombia
  • St.Thomas (USVI)
  • Puerto Rico (US)
  • Barceloneta, Machuca's Garden
  • Playa Negra in Vieques
  • Dominican Republic
  • Cocolandia, Palenque Beach, San Cristóbal
  • Baní Sand Dunes, Peravia, Baní
  • Black Stone Beach, Santa Cruz, Aruba

Asia

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North Atlantic

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  • Reynisfjara,[12] Iceland

North Pacific

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South Pacific

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Indian Ocean

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See also

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References

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  1. ^ "Archived copy" (PDF). Archived from the original (PDF) on 2018-06-20. Retrieved 2018-06-20.{{cite web}}: CS1 maint: archived copy as title (link)
  2. ^ "Magma, Lava, Lava Flows, etc". USGS. Archived from the original on 2010-06-03.
  3. ^ Hall, Jessica (8 June 2014). "Big Island: Kalapana and Kaimu Beaches; Destroyed by Lava". Hawaiicon. Archived from the original on 2017-05-03. Retrieved 2016-11-07.
  4. ^ Staton, Ron (7 January 1990). "Hawaii's Newest Black Sand Beach". Deseret News. Associated Press. Archived from the original on 2016-11-08. Retrieved 2016-11-07.
  5. ^ "Black sand and burnt feet: be careful on Auckland's West Coast". 100% Pure New Zealand. Archived from the original on 2016-04-23. Retrieved 2016-04-06.
  6. ^ "Top 10 Black Sand Beaches". 12 November 2008.
  7. ^ "The world's most beautiful colorful-sand beaches". Archived from the original on 2016-03-06. Retrieved 2016-02-24.
  8. ^ "Islands with Black Sand Beaches". Archived from the original on 2016-03-06. Retrieved 2016-02-24.
  9. ^ "Teixidelo, the only non-volcanic black sand beach in the world". Retrieved 22 April 2021.
  10. ^ "The Best Beaches in Panama | Frommer's". Archived from the original on 2016-03-03. Retrieved 2016-02-24.
  11. ^ "Treasure Beach". www.visitjamaica.com. Retrieved 2023-08-11.
  12. ^ "The main black beach in Iceland". 22 January 2021.
  13. ^ "Isaac Hale Beach Park // Pohoiki". lovebigisland.com. Retrieved 2019-04-18.
  14. ^ "Waipiʻo black sand beach". lovebigisland.com. Archived from the original on 2016-12-20. Retrieved 2016-12-13.
  15. ^ "Oneuli Beach Black Sand Beach | Maui Hawaii". Archived from the original on 2016-03-03. Retrieved 2016-02-24.
  16. ^ "One'uli Black Sand Beach". 16 November 2012. Archived from the original on 2016-02-26. Retrieved 2016-02-24.
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