Calcium nettle

The elemental distribution of Ca, Si, and Mn in the hair of the common stinging nettle Urtica dioica) obtained using the Oxford University PIXE microprobe. The color code for Ca is yellow, >3.4 M orange, 2.0-3.4 M red, 1.5-2.0 M dark blue, 1-1.5 M blue, 0.5-1.0 M light blue, 0.1-0.5 M white, <0.1 M. The color codes of Si and Mn are similar. The PIXE data show that the tip mainly is made up of Si (presumably amorphous silica), but the region behind is largely made up of Ca (calcium oxalate crystals). The base of the hair contains substantial amounts of Mn. The pictures were kindly provided by R. J. P. Williams. 

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