Hauckite, Fe33+(Mg,Mn)24Zn18(SO4)4(CO3)2(OH)81, is a new mineral found in the Sterling Hill mine. It is hexagonal, with Laue symmetry 6/mmm and unit-cell parameters a = 9.17(4), c = 30.21(9)A. The strongest lines in the X-ray diffraction pattern (d in A, intensity, hkl) are: 3.96 100 200; 7.8 90 100,101; 4.57 60 110; 3.02 60 0,0,10.

Hauckite is light orange to yellow with a light yellow streak. Cleavage is perfect parallel to {0001}. The Mohs hardness is approximately 2–3. The density determined by heavy-liquid techniques is 3.02, and the calculated value is 3.10 g/cm3. Hauckite occurs as euhedral crystals, tabular on {0001}, with {0110} and {0001} as the only forms present. The crystals occur in clusters resembling rosettes. Optically, hauckite is uniaxial (+) with refractive indices = 1.638(2) and ω = 1.630(2); it is pleochroic with O = golden brown, E = pale yellow, absorption O>E.

The composition, determined by electron microprobe, is: Al2O3 0.5, Fe2O3 6.0, MnO 17.1, MgO 13.2, ZnO 36.0, SO3 7.4 percent, with CO2 2.1 and H2O 17.7 percent (from the theoretical composition), sum = 100.0 percent. The empirical formula, based on cell dimensions and the calculated density of the pure end-member, is (Fe2.63+Al0.4)(Mg13.5Mn9.9Fe0.52+Zn0.2)Zn18.0(SO4)3.8(CO3)2.0(OH)80.8, in excellent agreement with the proposed formula.

Hauckite is found only in the Sterling Hill mine and is associated with calcite, serpentine, mooreite, and phlogopite on the type specimen; with pyrochroite, sussexite, and zincite on a second specimen; and with chlorophoenicite on a third specimen. There appears to be no direct relationship to any other species. Hauckite is named in honor of Richard Hauck of Bloomfield, New Jersey.

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