<p>Sedimentary rock phosphates contain much higher concentrations of potentially hazardous elements (As, Cd, Cr,Pb, Se and U)than igneous rock phosphates. Why?
Is it because U concentration in magmatic water is lower than in ocean water?
how could U accomodate in the apatite of igneous?</p>

CC BY-SA 4.0
2018-12-10T03:45:49.520Z
I found this [mining oriented description of how U becomes concentrated.](http://www.ga.gov.au/scientific-topics/energy/province-sedimentary-basin-geology/uranium-thorium-geology)
Keith McClary
CC BY-SA 4.0
2018-12-10T08:41:07.667Z
Interesting question. By the way, some magmatic apatites have lots of thorium, whereas there is almost no thorium in sedimentary apatites.
Gimelist
CC BY-SA 4.0
2018-12-10T17:26:05.733Z
Thanks for your answers and information. Very apprecited for that. One possible reason could be U become enriched in marine sedimentary by reworking after precipitation, in constract, igneous does not have that process.
孙雅杰
<geology><geochemistry>
why igneous phosphate rocks contain less uranium than sedimentary rocks?
孙雅杰
# why igneous phosphate rocks contain less uranium than sedimentary rocks?

(Asked by: username_0 on 2018-12-09)

Sedimentary rock phosphates contain much higher concentrations of potentially hazardous elements (As, Cd, Cr,Pb, Se and U)than igneous rock phosphates. Why?
Is it because U concentration in magmatic water is lower than in ocean water?
how could U accomodate in the apatite of igneous?

**Tags:** geology, geochemistry

> **Comments:**
> **username_1**: I found this [mining oriented description of how U becomes concentrated.](http://www.ga.gov.au/scientific-topics/energy/province-sedimentary-basin-geology/uranium-thorium-geology)  
> **username_2**: Interesting question. By the way, some magmatic apatites have lots of thorium, whereas there is almost no thorium in sedimentary apatites.  
> **username_0**: Thanks for your answers and information. Very apprecited for that. One possible reason could be U become enriched in marine sedimentary by reworking after precipitation, in constract, igneous does not have that process.  

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