Samsun 840 SSD - errors using gdisk
Before you toss the disk I suggest you connect it to you Mac and try running Disk Utility app. It's usually located in the Application/Utilities folder. Start this app and see if your disk shows up, Disk Utility has an option to erase the disk. You can erase the disk and then create a partition formatted to whatever format you want. After that, I'd run First Aid on the disk to see if there are any problems. Disk Utility will fix most problems it encounters. Then disk should be ready to use on your mac.