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About 5 years ago, I had a long discussion with some one on the Arch-metals list as to why there was medieval ironmaking in Northamptonshire, and again after 1850, but not between. The conclusion was that the Northamptonshire ores were too poor to be worked earlier (or possibly had been forgotten). Medieval ironmaking was probably based on gossan on the outcrop, presumably in this case due to the weathering of carbonate ore. We concluded that ironmaking ceased when this was exhausted. No doubt this is not relevant to Cornwall. Peter King 49, Stourbridge Road, Hagley, Stourbridge West Midlands DY9 0QS 01562-720368 [log in to unmask] -----Original Message----- From: mining-history [mailto:[log in to unmask]]On Behalf Of Tim Young Sent: 30 January 2008 09:54 To: [log in to unmask] Subject: Re: Gossan Dear Alasdair I'm actually doing some work on gossan iron ores from that area at present. Its not exactly the information you are after, but I'm writing up a late Iron Age iron smelting site on the west of Truro. The site lies adjacent to shafts associated with East Wheal Falmouth, but the site gives ample evidence for the smelting of gossan for iron around 2000 yrs ago. The work includes some geochemical and microstructural work on the gossan samples found stored (or hidden) in one of the Iron Age houses, as well as on the archaeometallurgical residues. It should be published shortly by the Cornwall Archaeology Unit. I assume that the sort of layered or boxstone textures I am seeing is what the mineral statistics would have called gossan - with perhaps this being on the verge of what they might have called iron ore (it is locally quite dense). I would imagine the ochre would have been very soft iron ore, with umber the manganese oxide dominated equivalent. The material I have shows voids filled with late stage Mn oxides (umber). At an earlier stage in this project I tried to locate gossan specimens from the area in various collections - in an attempt to work out how the term was used and to get comparative analytical data, but that effort unfortunately failed to track down any contemporary material. Best wishes Tim On 30 Jan 2008 at 9:31, Alasdair Neill wrote: > In updating the "Cornish Mines" volume originally published by Exeter > University, we are adding data from the Mineral Statistics omitted in > the original edition. This includes data for "gossan" which was > produced by mines particularly in the Wheal Jane area. > The geological meaning for gossan is of course well known (the > ferruginous weathered capping typically found in association with > sulphide mineralisation), but can anyone say what it was used for > commercially? There are references to attempts to extract gold from > gossans in that area in the early 1850's gold boom, but it seems > unlikely this ever led to anything. > The Mineral Statistics data lists it seperately from ochre, umber, > & > iron ore which may have had similar uses. > > Alasdair Neill. -- Dr Tim Young Email: [log in to unmask] Web: www.geoarch.co.uk Phone: 07802 413704 Fax: 08700 547366