A new occurrence of the Ca-borosilicato axinite has been identified in a pegmatilic vein cutting metamorphosed Biwabik Iron-Formation on the eastern Mesabi Range, Minnesota. The mineral occurs as grayish-brown patches associated with large anhedral crystals of quartz and K-feldspar and with small amounts of Fe-rich chlorite. The axmite is highly manganoan and corresponds to the formula:

Determined unit-cell parameters are: a = 7.161, b = 9.190, c = 8.978 Å, α = 88.26°, β = 81.80°, γ = 77.26°, V = 570.3 Å2. Earlier reports of systematic variations in composition between the fine and coarse separated fractions were not verified by microprobe analyses. However, significant variations, particularly in total FeO, MnO2, and Al2O3, exist between different grains.

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