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Phil, Been thinking about your questions: Can anyone enlighten me on how dressing processes would have differed between lead and zinc at mines, where both metals are known to have been exploited? ANSWER: Lead and zinc sulphide ores are generally found together. Dressing used gravity processes ( until froth flotation was invented). The difference in the specific gravity of the minerals meant that the same equipment could and was used to separate the two ores, either from each other or from other minerals. (There were difficulties in seperating the zinc ore from minerals of similar specific gravity). I'd be particularly interested to know if there are any specific forms of archaeological evidence that might survive, exclusively associated with zinc dressing at British mines. Any published examples, preferably in England, would be particularly welcome. The 19th Century dressing plant at Nenthead produced lead and zinc dressed mineral, although it was built to process lead ore. This plant was replaced in 1910 by a gravity plant, built on the same site, designed to process zinc ores, which also continued to also produce lead ore. This plant was closed down around 1922 and mothballed. It was resurrected in 1936 to produce lead ore and worked for about 18months before being mothballed again. In 1943, the building was re-equipped as a froth flotation plant to dress zinc ores from the old dumps and closed down again in 1945. The gravity equipment was largely removed in 1943. The same plant was then used from around 1950 to 1963 to process lead, zinc and fluorite ores. The equipment was then removed and 50% of the building demolished. The remaining 50 % is currently used as a bus depot and the locations of zinc dressing gravity equipment ( 1910 phase) can be seen. No archaeology has been done on this site. Adjacent to the 1910 building was a magnetic separator plant. this was apparently where the zinc concentrates were roasted and subject to a magnetic process. The intention was to remove the siderite and pyrites which devalues the dressed zinc concentrates and is difficult to separate via gravity means ( Similar SG). This building was demolished before it was recorded ( other than photographs). On early editions of the OSMaps for Nenthead is a "spelter works". There is also a photograph. This site is approx 400 metres to the north of the Nenthead dressing plant. From the size of the site and the photo, this looks to me like a crushing mill and possible small roasting furnace for zinc ores. Building has been demolished and site landscaped. No archaeology has been done on this site. This plant was linked to Brownley Hill and Gudhamgill Mines. Nentsberry Mine nearby also produced zinc ores and had a small dressing mill. Again, demolished and unrecorded. Threlkeld and Thornthwaite mines, near Keswick, also produced zinc ores. I think that the dressing mills were demolished after closure and the sites cleared. Mill Close Mine produced zinc concentrates - can someone with more knowledge of that site discuss the dressing plant? This may be the only English example where froth flotation was used for zinc sulphide dressing, unless there was an example in Cornwall? West Shropshire mines produced zinc concentrates - ditto as above? By the way, your question illuminates an enormous gap in our collective knowledge of zinc mining in the UK. Peter Jackson