James Watt's Snuff Box?

Hello I am just after any information about this snuff box that I inherited.

I do not for a fact know if it is a snuff box but that is what I am told. Dimensions are approximately 30mm wide x 20mm high x 24mm deep.

I think it is made of silver but can not be 100% sure.

There are no marks or stamps that I can see inside of out though I have not touched the liner or the material that covers the outer bottom of the box.

All I know about the history is on the card that came with it. The card reads:

To Heather McColl (that is my mother)
A snuff box. Well over 100yrs may be 200 years.

James Watt
Margaret Watt
Archibald Glen
Josephine Glen (Doepel)
Joesephine McColl (Doepel) (my great grandmother)

Any help would be great.