Magnetite. . . generally occurs at the conjunction of limestone, volcanic rocks, both of Upper Triassic age, and younger intrusive rocks of intermediate composition. Orebodies tend to be localized in small areas of intense deformation. The bulk of the iron was probably derived from the thick Karmutsen Group of volcanics underlying the limestone. Considerable volumes of the Karmutsen must have been incorporated by the ascending magmas, and excess iron was probably expelled with the residual magmatic fluids. Replacement was probably accomplished largely by individual ions and molecules diffusing. . . out along grain boundaries and cleavage cracks to points of a Hack on calcite and silicate crystals.

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