If difficulties arise from attempts to partition a micro SD card, be sure the adapter which you plug it into is not locked.
I was attempting to re-partition the 2nd partition for my tablet to make more room when GParted kept giving me these warning that 'File System was mounted as "Read-only"'. WTF, i thought.
I first attempted to unmount(sudo umount -f /dev/sda3), get root access, and alter permissions for the card (normally this would suffice). But, low and behold, GParted again complained i do not have write access to card. Again, i thought WTF.
Then, a bright white lightbulb flashed over my numb-skull....."Do you have the adapter locked?"
Shoot, how stupid!
In summation, whenever formatting, partitioning, or writing to your micro SD card, always be sure the SD card adapter is not, itself, locked.