# Why mineral veins?

**URL:** <https://boards.straightdope.com/t/why-mineral-veins/358257>\
**Category:** Factual Questions\
**Created:** [May 25, 2006, 11:40pm UTC](https://boards.straightdope.com/t/why-mineral-veins/358257 "2006-05-25T23:40:55Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Rune](https://avatars.discourse-cdn.com/v4/letter/r/e68b1a/32.png) [@Rune](https://boards.straightdope.com/u/Rune)\
**Post date:** [May 25, 2006, 11:40pm UTC](https://boards.straightdope.com/t/why-mineral-veins/358257/1 "2006-05-25T23:40:55Z")

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Why are minerals found in Earth veins? Given the violent beating and mixing the Earth has had to endure why aren’t the minerals more or less evenly distributed throughout the Earth? Or alternatively the lightest on top and the heavier further down?

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**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\
**Post date:** [May 26, 2006, 4:29am UTC](https://boards.straightdope.com/t/why-mineral-veins/358257/2 "2006-05-26T04:29:11Z")

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I’m not a geologist, so I hope others will correct or expound.

When igneous rock is in liquid form, minerals are distributed rather evenly. As it cools, the various minerals become solid at different times, and are deposited as veins. The whole blob of igneous rock doesn’t cool all at once.

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**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\
**Post date:** [May 26, 2006, 7:47am UTC](https://boards.straightdope.com/t/why-mineral-veins/358257/3 "2006-05-26T07:47:43Z")

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IANAG either, but also, fluids (either solutions or lava) are often forced through fissures in existing rocks, depositing minerals along the way, or transforming the composition of the immediately surrounding rock.

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**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\
**Post date:** [May 26, 2006, 4:01pm UTC](https://boards.straightdope.com/t/why-mineral-veins/358257/4 "2006-05-26T16:01:42Z")

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[Here’s](http://www.utexas.edu/tmm/npl/mineralogy/Mineral_Genesis/HydrothermalAqueousSolutio.htm) a link that explains some of the ways that veins form.

> [@](#):
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> A large number of economically valuable ores and mineral deposits exist as tabular or columnar bodies called veins… Typically, the veins form through the precipitation of minerals from high- to low-temperature aqueous or hydrothermal solutions in pre-existing fractures, fracture zones, and solution cavities.