Query file system type for yet-to-be mounted volumes?

[Modulok]

How does one determine the file system a disk uses, for disks that are
not yet mounted? Example: You're handed a disk that has been sitting
around in a closet for years, with no idea what it was used for. The
department manager tells you to see what it contains.

How do I mount it, if I don't already know what file system it uses?
Is there a command to query this? Trial and error doesn't seem like
the ideal solution.

-Modulok-