gîte métallique

CONT: La majeure partie des hydroxydes se trouve dans les zones d'oxydation des gîtes métalliques et dans les roches altérées [...] Oxydes et hydroxydes sont les principaux minerais de fer, chrome, manganèse, uranium, étain, aluminium, niobium, tantale.

CONT: It has long been recognized that specific regions of the world possess a notable concentration of deposits of a certain metal or metals, these regions are known as metallogenic provinces. Such provinces can be delineated by reference to a single metal ... or to several metals or metal associations. In the latter case, the metallogenic province may show a zonal distribution of the various metallic deposits.
CONT: ... in the forties and fifties much emphasis was still placed on the magmatic-hydrothermal theory for the origin of the majority of metallic deposits.
CONT: In supergene sulphide enrichment the minerals of economic interest are carried down into hypogene (primary) ore where they are precipitated with a resultant increase in metal content, whereas in the case of iron and manganese ores it is chiefly the gangue material that is mobilized and carried away to leave behind a purer metal deposit.