[mass noun] An iron-containing secondary deposit, largely consisting of oxides and typically yellowish or reddish, occurring above a deposit of a metallic ore.
- ‘Here unusually lustrous crystals to 2.5 cm across occurred in limonite-malachite gossan.’
- ‘Some of these veins reached the surface where, in the enclosing gossan, the stibnite has been subjected to oxidation.’
- ‘It was found in gossan from a dump of one of the small mines on the southeastern side of the mountain on the World's Fair claim group.’
- ‘Most are free of matrix, although some of the paler green or greenish-yellow groups are on gossan and are associated with cream to bluish cerussite.’
- ‘In deposits that have been uplifted and exposed on land, the upper sulphides and oxides are invariably oxidized and weathered to a variety of secondary minerals (‘gossan’) by circulating meteoric water.’
Late 18th century: of unknown origin.