The Sokoman Formation, also known as the Wabush Iron Formation, is the ore-bearing formation in the Wabush Lake-Mount Wright area. It consists of mainly semi-massive bands or layers and disseminations of magnetite and/or specular hematite in recrystallized chert and interlayered with bands of chert with iron carbonates and iron silicates. The Sokoman Formation is subdivided into Lower, Middle, and Upper Members.
The Lower Member (LIF) consists of a 0 - 75 m thick sequence of fine to coarse grained banded quartz-carbonate, and/or iron-carbonate (i.e. siderite, ankerite and ferroan-dolomite), and/or iron silicate ( i.e. grunerite, cummingtonite, actinolite, garnets), and/or iron-carbonate-silicate units. Mixtures of these units can occur both vertically and laterally. This member may contain iron ore locally.
The Middle Member (MIF) forms the principal iron ore unit and consists of a 45 - 110m thick sequence of quartz-magnetite, and/or quartz-specularite-magnetite, and/or quartz-specularite-magnetite-carbonate, and/or quartz-specularite-magnetite anthophyllite gneiss and schist units. Actinolite and grunerite rich bands can be present in this member. Martite can also occur in weathered zones by alteration of magnetite.
The Upper Member (UIF) consists of a 45 - 75 m thick sequence similar in composition to the Lower Member and can generally only be differentiated through their contact relationships with the overlying and underlying formations supported by detailed structural interpretations.
The hydrous iron oxides, limonite and/or goethite, have been observed in all members of the Sokoman Fm. Limonite and/or goethite are present in weathered and fractured zones and are derived primarily from the alteration of iron carbonates. Pyrolusite (MnO2) was also observed in all members of the Sokoman Formation and is typically associated with surficial or supergene enrichment, extending to depth along and