File system can be of any type. So to know the file system of a mounted partition below command will work.
df -T
Output will be similar as below
[root@kk]# df -T
Filesystem Type 1K-blocks Used Available Use% Mounted on
/dev/mapper/VolGroup-lv_root
ext4 49331000 5599340 41225728 12% /
tmpfs tmpfs 515444 88 515356 1% /dev/shm
/dev/sda1 ext4 495844 31169 439075 7% /boot
/dev/mapper/VolGroup-lv_home
ext4 51339916 480208 48251788 1% /home
/dev/mapper/vg–jenuI-logiclvol–jenu
ext3 138829 138829 0 100% /root/logvol