TheYinyanporphyrytindepositisablinddepositassociatedwithasmallgraniteporphyrystock.ThepetrologyandgeochemistryoftheYinyangraniteporphyrysuggestthatitisgeneticallyofthetransfor-mationtype,emplacedatthelatestageoffractionalcrystallizationwithinahigh-levelmagmachamber.Ore-formingfluidsarederivedpredominantlyfromthegraniticmagmaandtheyinteractwiththewallrocksintenselywhenfindingtheirwayupwardsthroughthegraniteporphyry.Fromthelowerpartoftheporphyryupwardsthefollowingalterationzonescanbedistinguished(a)slightlyalteredgraniteporphyry(withweakpotashfeldspathization),(b)protolithionite-quartzgreisenizationzone,(c)to-paz-quartzgreisenizationzone,(d)senicite-quartzsericitizationzone,and（e）silicificationzone(quartzcoreatthesurface).Tinmineralizationisrelatedtogreisenization,especiallytotopaz-quartzgreisenization.Rockandore-formingtemperaturesandoxygenfugacitiesareestimated,respectively.TherearesignificantdifferencesinmanyaspectsbetweentheYinyanporphyrytindepositandvolcan-ic-subvolcanicporphyrytindeposits.
