Vegetables Gardening - Growing Organic Vegetables

Six weeks ago I bought a few extra bags of gypsum from home depot to make pre-plant mix. It was wet when I purchased it but I figured it would dry out in my shop. Six weeks later (today), I opened it and it is still wet. It feels like regular muddy dirt with small rocky pieces in it. Nothing like the white powder I was used to when I purchased gypsum from a farm supply.

Will this product will still work if I dry it out? Is it just a lower grade version? Or is it possible that the guys mining the stuff that day accidentally scooped up something else and tossed it in the bag? I'm used to a white powdery flour like substance that mixed up and dusted nicely onto my soil. I don't have any of that left and I'm in a pinch because I live several hours from a large store (we're way out in the countryside). I want to get my peppers in the ground, but all I have in terms of gypsum is this wet gritty sludge that probably won't dry out for a while Any advice would be great.  

This is what I purchased previously- it worked great: https://www.groworganic.com/products/diamond-k-solution-grade-gypsum-50-lb

This is what I purchased at Home Depot: Classic Stone Classic Stone 40 lb. White Blend Pulverized Gypsum - (64 Bags/ Pallet)-R1GYP-C - The Home Depot

Thanks,

Luke