Or make up some other name if you wish
That's ok. I chalk everything black up to Fe/Mn. In all the reading I've done, there's not been other suggestions, except maybe bitumen of some grade. But I don't think that's black when it gets thin, stain-like. Thanks for answering.
Richard, do you know what the other chemical compounds might be that you mention in the last sentence.; do you have a few examples?
Actually I don't, so I edited that line to reflect that. Thanks! (And sorry I don't have any good ideas for it)
That's ok. I chalk everything black up to Fe/Mn. In all the reading I've done, there's not been other suggestions, except maybe bitumen of some grade. But I don't think that's black when it gets thin, stain-like. Thanks for answering.
Richard, do you know what the other chemical compounds might be that you mention in the last sentence.; do you have a few examples?
Actually I don't, so I edited that line to reflect that. Thanks! (And sorry I don't have any good ideas for it)