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Hi Barry, Galena, while silvery bright when fresh, may tarnish to bluey tones, or in time from that to a brownish-bronze and eventually to dull grey-white as a thin coating of lead sulphate forms on its surface. Galena on old mine-tips will always be the latter colour unless bashed with a hammer! It is said that in Cardiganshire the miners reckoned that galena that tarnished blue was silver-rich. However I've seen this tarnish on galena from silver-rich mines (eg. Darren) and silver-average ones (eg. Frongoch). The difference being along the lines of 30oz/ton and 3oz/ton! However it starts getting complicated here because the "silver in galena" at Darren and other famous mid-Wales silver producers was present as inclusions/intergrowths of another mineral, tetrahedrite - a true silver- ore carrying up to 20wt% Ag. Whereas the galena at Frongoch belongs to a later mineralising event which did not include tetrahedrite! As noted by another poster, heavy brown ores on mine-tips in lead-mining areas tend to be zinc-blende. Hope that's useful somehow! Cheers - John