I think it would be helpful to contextualize and clarify the specific image in greater detail - to walk the viewer through the landscape (imagry) that is being presented. Is the mud common? Is this a specific brand of mercury? does that matter?
The image's subject seems to be mercury - though one would argue from the textual description that the subject is in fact the bodies that come into contact with this (seemingly invisible, harmless, beautiful) substance.
The image is ethnographic in that it is representative of a compounding of components at a single field site. To the design statement I would add a statement regarding the photographer's choice to foreground the bottle of mercury (with the mine in the background). What does this spatial representation do for the reading of the image?