The Lexington Mountain region is underlain by a series of metamorphosed Cambrian to Devonian sedimentary and volcanic rocks of the Lardeau Group which overlies the Lower Cambrian Badshot Formation in the east. The predominant structural features in the area are northwest trending and plunging overturned folds and regional semiconcordant to concordant faults. The strata within these structures are steeply east dipping with a variable plunge to the northwest.
Three distinct northwest striking limestone-chlorite schist contact zones spaced at roughly 1 kilometre intervals cross the property. The Index Formation (Lardeau Group) hosts similar mineralization within these zones and may represent either folded repetitions of the same contact or stratigraphic repetitions of similar depositional environments. The mineralization occurs as both disseminated and massive zones of galena, pyrite and sphalerite associated with dolomitized limestone and silicification invariably developed with siderite-rich zones containing hematite and magnetite localized along the limestone-chlorite schist contacts.
The Alma showing consists of intermittent occurrences of massive bands, streaks and lenses of galena-sphalerite in crosscutting quartz-carbonate veins within siderite alteration zones. The phyllite is sericitized and limestone is ankerite-dolomite altered.
This area was originally explored in the late 1800s and early 1900s when prospectors discovered widespread precious and base metal mineralization. During 1985-86, Consolidated Trout Lake Mines Ltd. and Jazzman Resources Inc. acquired interests in two separately owned but interlocking claim groups (termed the Lexington Creek and Lime Dyke Claim Groups). In 1985, prospecting and reconnaissance geologic mapping was carried out on behalf of Lardeau Development Corp. and Triple M Mining Corporation. In 1987 and 1989, Consolidated Trout Lake Mines Ltd. established a grid and conducted soil sampling, ground magnetometer and VLF-EM surveys, geological mapping and rock sampling and an airborne geophysical survey. During 2006 through 2009, Mineral Mountain Resources Ltd. completed programs of prospecting, geochemical (soil, silt, talus fines and rock) sampling and an airborne geophysical survey on the area as the Kootenay Arc property.
