Mounting LVM2 volume gives me 'mount: you must specify the filesystem type'

Mounting LVM2 volume gives me 'mount: you must specify the filesystem type'

I have a LVM2 Volume Group 'vgXEN' with a Logical Volume in it called
'test-disk'.
This is the output of lvdisplay:

--- Logical volume ---
LV Path /dev/vgXEN/test-disk
LV Name test-disk
VG Name vgXEN
LV UUID lHSgfx-wnY2-OtRO-zw7l-9SFA-mnht-KgK9MO
LV Write Access read/write
LV Creation host, time DRAKE, 2013-08-26 12:02:08 +0200
LV Status available
# open 0
LV Size 10.00 GiB
Current LE 2560
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 4096
Block device 253:4
And this is the output of lvscan:
ACTIVE '/dev/vgXEN/test-disk' [10.00 GiB] inherit
Now when i try to mount this logical volume with the command i get an error:
mount /dev/vgXEN/test-disk /mnt/test
mount: you must specify the filesystem type
My operating system is 'Linux DRAKE 3.2.0-4-amd64 #1 SMP Debian
3.2.41-2+deb7u2 x86_64 GNU/Linux'.
Searched the Internet but couldn't find anything useful. Can anybody point
me in the right direction please ? Thx !