Dwornikite, (Ni,Fe)SO 4 .H 2 O, a member of the kieserite group from Minasragra, Peru

A new nickel sulphate monohydrate is described from V-sulphide ore from Minasragra; it occurs associated with patronite (VS ₂ ) with various sulphates, sulphur and bitumen. Dwornikite forms fine-grained white aggregates mixed with other oxidation products. Indexed X-ray powder data are tabulated; strongest lines 3.342(100) , 4.732(70), 3.024(70), 4.754(50), 3.293(35), 2.491(35) A; a 6.839, b 7.582, c 7.474 A, beta 117.85o; space group C2/c. XRF gave NiO 39.0, FeO 9.3, SO ₃ 42.4, = 90.7; D _calc. 3.34 g/cm ³ ; mean refr. ind. approx 1.63. Unit-cell data for the synthetic end-member compounds NiSO ₄ .H ₂ O and FeSO ₄ .H ₂ O and new X-ray powder data for retgersite (NiSO ₄ .6H ₂ O) are given. The name is for E. J. Dwornik, mineralogist with the U.S. Geological Survey.-R.A.H.