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Published online by Cambridge University Press: 05 July 2018
An unnamed Fe3+ analogue of hematolite is described from Sterling Hill, New Jersey and Långban, Sweden. Eight microprobe analyses are in good agreement with ratios derived from a prior analysis which yielded: Al2O3 0.24, Fe2O3 10.85, MgO 10.61, MnO 41.76, As2O3 6.65, As2O5 15.29, H2O 13.23 (rem. = 1.63), sum = 100.26 %. Single-crystal study indicated that this compound is hexagonal with a = 8.28 Å, but the value of c could not be well-defined due to complex polytypism giving rise to diffuse and poorly resolved reflections along c*. In one case, a value of c = 72.69 Å was dominant. All values that could be determined were multiples of approximately 12 Å. The strongest lines in the X-ray powder diffraction pattern are: 2.400(100), 1.563(100), 6.09(80), 3.42(50), and 5.13(50). This compound is dark red and occurs as platy hexagonal crystals in clusters associated with a wide variety of species in varied assemblages. It remains unnamed because of the ambiguity arising from polytypism.