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The tetragonal rutile grows upon the rhombohedral titanic iron, so that its prism of the second order, ∞ P ∞ (100), coincides with the basal pinacoid of the latter mineral, while its vertical axis has the direction of one of the intermediate lateral axes of the iron ore.

Rutile Growing Upon Titanic Iron

The tetragonal rutile grows upon the rhombohedral titanic iron, so that its prism of the second order,…