Bournonite with Quartz

Quartz; Bournonite forming thick cogwheel blades; Herodsfoot mine; need more be said?  One of the true Cornish classics and so well represented in this charming small cabinet specimen.  Bournonite is a lead-copper sulphosalt, meaning these metals form a compound with antimony and sulphur.  Some of the best Bournonite specimens in the world came out of Herodsfoot mine at Lanreath, close to Liskeard.  This locality and its minerals are extensively researched and photographed by Roy Starkey in his Mineralogical Record article ‘The Herodsfoot mine, Lanreath, Cornwall, England’ (pp. 411-486, Vol 43, No. 4), now just approaching its ten anniversary of publication!  Intermeshed cogwheel crystals of gunmetal grey Bournonite up to 2 cm across richly adorn a matrix of mixed massive milky Quart and Bournonite.  The crystals have a subdued satin to metallic lustre, often with a steel-blue cast and slight iridescence.  Characteristic for Herodsfoot, small, drusy clusters of Quartz crystals nestle between the Bournonite crystals. It’s a great specimen and not badly priced at $2500.  It comes with Mike Brooke, Mike Merry and Robert Hauck labels.