Recently I needed to read a recently bought pendrive with 16 GB of memory, and I discovered it was formatted with the EXFAT filesystem.
It was mounted transparently in OSX, but in Fedora Linux 19 I discovered the commands I remembered reported unknown filesystem. The solution is easy, just install the fuse-exfat package:
yum install fuse-exfat
mount /dev/sdb1 /media
Assuming sdb1 is the pendrive.