Realgar is an important auriferous mineral in the Manaoke large_size ultrafine disseminated gold deposit. In this paper, the authors have studied mineralogy of realgar from the deposit,including its mode of occurrence, physical properties, chemical composition, X-ray diffraction features, cell parameters etc. The results show that the realgar is a low-temperature As-deficient variant (β-AsS) containing Sb, Fe, Hg, Au and Ag. Its unit cell parametersa09.357 (3),b013.581(4),c06.613(3)A;,β106°34′(2) and V0805.51(37)A3; are somewhat bigger than those of normal" realgar (β-AsS) from other areas. On such a basis, the modes of occurrence of Au and Sb in realgar crystals in relation to gold prospecting are tentatively discussed.