Norman Baron 'Henry de Ferrers'

[D.Send]

Hi,
Has anyone got access to source information, concerning the medieval Norman Baron 'Henry de Ferrers' or his descendants working Derbyshire mines? Apparently he held leases to exploit lead mines, and minted silver coins... according to websites.
But the sites don't specifically quote their sources...
D.Send.

 

[AR]

A bit off topic  :-\ and more an Aditnow than a UKC question, but off the top of my head, if there is any original source information it would most likely be in the National Archives, in the Duchy of Lancaster's records. There may also be archives held by the de Ferrers or their descendants but not necessarily publicly accessible. For modern published sources, I believe Ian Blanchard did some work on medieval lead working in the Peak District?