how to tell if lumber is treated with the bad stuff if it's not tinted green or labeled?

Steve tore down a falling down shed for someone for the lumber...a small amount of it is looking suspicious now that it's cleaned up and stacked...not greenish exactly.

It was an old small shed...old enough to be the arsenic laced wood

Is there any way to tell if it's treated lumber?
There is some greenish tint but mabe algae since it's not all over the boards?

Hello Judith!

I usually think wood is ok if it does not have the little staple marks of pressure treated wood.  I am probably just naive though.  This does look like the nice green of algae rather than the yucky green of treatment.  

Does it stink or feel yucky when you touch it?    You might cut into it and look at the wood shavings.  Alge would be just on the very surface.  If the green is treatment it may be greener just below the surface where it has not been weathered off.

If something gives me any kind of a yucky feeling, I don't use it near my garden or livestock.   If it gives me a real yucky feeling I get it off my property.  

Based on the photo, I would consider it safe.  

I'm going to further agree with the previous opinions. To me, that looks like surface microlife.

That also looks OK to me. I've read that you can burn a splinter of the wood and if there's a bunch of green in the flame it's from copper arsenate.

Another test is to put a chunk into a hot fire and see if the ash that forms is an unusual colour. CCA treatment will produce a bright green ash because of the copper content. Sometimes the presence of chromium will give it a yellowish cast, more chartreuse.