Hmm? Blackish color shouldn't happen at all unless it gets exposed to excessively hot and moist conditions. Typically the S-GH will clump up but should break up fairly easily when stirring with the scoop.
If the container was opened it should technically be used in 45-60 days for best results and to avoid any moisture issues if you live in a humid hot climate.
We are releasing an improved version of S-GH in the next 2 weeks that doesn't really clump up at all and is flavored better.