using hardened mortar?

[weo]

Hello all. I'm pretty sure you aren't supposed to use hardened bags of mortar to replace a few bricks in a chimney, but is this true even if the bags were stored inside, just in a humid part of the country, and I am able to return the mortar to powder just by crushing it in my fingers?
Thanks

 

[Stacy E. Apelt - Bladesmith]

Old bags can get pretty stiff, but if they break down to powder, they may still be good.

Mix some with water and see if it sets up like it should. If it does, it is good.