Sandisk Ultra MicroSDxc 64gb not readable

I had my card in a Samsung Galaxy s3 which I no longer own. I use a sandisk micro adaptor to put it in my Apple Macbook Pro however everytime I insert it i get this message, “The disk you inserted was not readable by this computer.” No matter what I try I can’t get anything to read it. Checking the status of the card it has all my memory on it but its status is unmounted. Tried to mount it but its having none of it. Running out of ideas of how to get it working and get the stuff stored on it off of it. Think the only thing I can do is insert it back into a samsung product to see if that works. Any help or advice much appreciated. Thanks in advance.

Is it still in its native format of exFAT? Your Macbook may not support (be able to read) that format. You may have to re-format it as FAT32.