I have placed 200GB SanDisk card inside Nifty adapter and put it into SDXC slot in my Mac.
I want to use it as permanent & encrypted storage. Unfortunately encryption requires GUID partition which I tried to create but without any luck. "Partition" option – under "APPLE SD Card Reader Media" in Disk Utility – is greyed out.
I'm stuck.
P.S. I own Late 2013 Macbook Pro Retina 13" with MacOS Sierra (v10.12.6) installed.
Best Answer
It will probably be supplied as MBR, so you need to Erase first.
Partition doesn't let you change the underlying Partition Map format, MBR->GUID