I believe copper is the active ingredient in cutrine. If it drops out...what'soing to kill the weeds?
Cutrine Plus pamphlet quotes...
Copper Ethanolamine Complex, Mixed (Mono CAS#
14215-52-2 and Tri CAS# 82027-59-6)*..........27.9%"
"This product is a liquid copper-based formulation containing ethanolamine chelating agents to prevent the precipitation
of copper with carbonates and bicarbonates in the water."
Even though the "ethanolamine chelating agents" are supposed to keep the copper from falling out, something has solidified and I'd bet that those ingredients are important to the nature of the herbicide.
Disclaimer - I'm no herbicide expert or cutrine user for that matter. Just my opinion...I would dispose of it or use it with little hopes of any killing effect.