Yesterday I replaced my kitchen faucet and in doing so I needed to turn off the water at the valve under the sink. After I was done I noticed the cold water valve has developed a small drip which it wasn't before.
If you look at this image
My question is does the valve come apart by unscrewing where the red arrow points and is a general replacement valve part or is this more serious in that the pipe needs to be cut and a new valve soldered in?
Also in this image
and finally all the green covering the valve, does that indicate a high concentration of something in my water?
Thanks alot !!