Admiral:
Something sometimes encountered by archaeologists, are bones stained green or blue-to-black by metals worn by the dead reacting with acids in the soils. Example the Green Lady of Pompeii:
The Green LadyWhile people with less means were found without green bones, i.e. without metal wealth about them.
�,� bones of a wealthy woman were stained green from the reaction of the metal jewelry she brought
with the bone (there was a green man with her too �?" above �?" was the owner of the cellar)
�,� Primary Source: bones show she was pregnant
Now, this opens up for some oddball paintjobs on Undead skeletons and skeletal remains such as on the Road of Skulls.
To the left a chicken femur stained by copper salts, to the right one stained by iron compounds (starts to look like Diablo II):

A piece of cattle bone stained by copper sulfate:

A piece of skull from Wessex with a green spot where the cranium has been in contact with brass fittings inside the coffin:

A green-spotted bone:

Bones from a wealthy man who died in Pompeii’s suburb Oplontis. One of the bones is green on the left side. The humans which died around him had all at least one or two green bones and lots of coins and jewelry about themselves, while another group of people in the other end of the same cellar had no green bones and no precious metal to speak of:

