Could someone help me learn about these two quarters?

[hypoman]

Hey everyone. I found two quarters going through my brothers coins and was wondering if anyone could tell me what is wrong with them. One of them has turned black on both sides. The other is stained on front but that's not what I want to know about. The back is really fuzzy and there is no reeding , just a groove. I can see a little bit of reeding on a small section but the rest is just a groove. I hope these pics help:

 

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[vayank54]

What is the date on the dark one? It looks like a clad quarter ( made after 1964) that has been in the ground for a good amount of time. The other I have no idea on.

 

[hypoman]

The date on it is 1987. So this sort of thing happens when in the ground a long time? Thanks for the info on that one!

 

[vayank54]

Yeah the clad coins will turn dark. silver will stay the same color or sometimes turn black

 

[ivan salis]

depends upon the chemical make up of the soil -- coins lost in acidic soil often turn black -- in high iron areas --reddish often