Eleven pyrite samples from a certain gold-silver ore deposit in Zhejiang province have been examined to find out the relationship between such isomorphous impurities in pyrite as Co,Ni, As, Sb and the 57Fe Mossbauer parameters at 298 ºK. As a result, the following conclusions have been reached. (1)The relationship between the electric quadrupole splitting (QS) of pyrite and its arsenic content obtained by means of linear regression of six pyrite samples with available quantitative arsenic analyses is QSpr=0.612+ 0,00925As(at%).Antimony impurity has a similar but a bit smaller effect on the QS of pyrite. (2)The linear equation for the relationship between the QS of pyrite and its cobalt content obtained from the QS and Co contents of pyrite as well as synthesized Co0.25Fe0.75S2 and Co0.99 Fe0.01 S2 is QSpy-co=0.608一 0,0087Co (at%).Nickel impurity has a similar but somewhat larger effect on the QS of pyrite, (3)The QS of pyrite depends on the atomic percentage ratio of its impurities(As+Sb)/(Co+Ni)，i, e.，the QS value increases with the growing ratio. (9)As the contents of impurities in pyrite are related to formation condition, the QS of pyrite might find application in such aspects of ore research as the genesis of ore deposits, the division of ore-forming stages, the metallogenic zoning and the mineral assemblages, and therefore can surely play its role in the prospecting, evaluation and exploration of ore deposits,