Not, in fact, an urn, but a damaged solid piece of the semi-precious mineral known as bluejohn, 19cm high.
In the UK, bluejohn, also known as Derbyshire spar, is found only at Blue John Cavern and Treak Cliff Cavern in Castleton, Derbyshire.
It is a rare form of fluorite, with bands of either purplish blue, or as in this case, a yellowish colour.
