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Hydration. A rock weathering process. By: Maple, Isabel, Michelle, Yu Teng. Hydration Defined.
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Hydration A rock weathering process By: Maple, Isabel, Michelle, Yu Teng
Hydration Defined A process whereby water is absorbed into certain existing minerals in a rock, causing the rock to change physically (by expansion) and chemically (by its composition). Also causes the partial decomposition of the rock - E.g. CaSO4 CaSO4∙2H20 Gypsum Anhydrite
Hydration Processes • Addition of water to rock minerals causes the disruption of crystalline structure of minerals as new compounds are formed • Rock increases in volume, causing stress on the rock • Zones of weakness, known as joints develop in the rock, increasing the overall permeability of the rock. • By spalling, pitting and flaking, rock grains break down, forming a decaying rock. Granite
Factors affecting Hydration Climate • At arid and semi- arid areas (due to wetting and drying associated with sudden downpours or the spread of dew) • Wet and warm areas (due to high level of moisture) • Glacial and peri-glacial areas (due to high level of moisture) • Presence of joints (lines of weaknesses) in rocks→ cracks allow more water to enter the rock→ speed up process of hydration • Grain size→ the bigger the grain size, the faster the rate of hydration • Resistance/ Mineral composition of rocks→ less resistant rocks react more readily with water→ faster rate of hydration
Hydration Products/Landforms Rock Increases in Volume -Formation of Joints -Signs of Cracking; Granular Disintegration -Rock weakens Formation of new mineral compound Joints in rocks
Hydration Products/Landforms Change in colour Obsidian Perlite Obsidian and Perlite
Hydration Example Nevada, USA -Desert and semi-arid climate -In 2008, Nevada produced 1401000 pounds of gypsum from their mines and as well as had perlite mines. Nevada Mine Nevada Mine
Hydration Sources • http://www.globalchange.umich.edu/globalchange1/current/lectures/soils/soils.html • www.stonecaretechniques.com/8_m.htm • http://geology.about.com/od/rocks/ig/igrockindex/rocpicperlite.htm • http://minerals.state.nv.us/forms/mining/MajorMinesOfNevada/mm2008.pdf • http://www.answersincreation.org/curriculum/geology/geology_chapter_12.htm • http://www.westernminingandminerals.com/gypsum-vs-anhydrite-article.pdf • d