The Lodestone Mountain magnetite deposit occurs at the summit of Lodestone Mountain, 23.5 kilometres due west of Princeton.
The area is underlain by intrusive rocks of the Early Jurassic Tulameen Ultramafic Complex. This ultramafite body intrudes metamorphosed volcanics and sediments of greenschist to amphibolite grade of the Upper Triassic Nicola Group, in the western margin of the Nicola belt. The body trends north-northwest for 20 kilometres, between Grasshopper Mountain and Arrastra Creek, roughly paralleling the contact between the Nicola Group and the Eagle Plutonic Complex to the west. The unit ranges up to 6 kilometres in width, and is at least 3 kilometres wide over most of its length. This intrusion varies in composition from dunite to gabbro, with the most abundant lithology being a coarse-grained pyroxenite.
The deposit is hosted in a belt of hornblende clinopyroxenite, extending along the western margin of the complex. The belt is flanked to the west by syenogabbro and to the east by olivine clinopyroxenite in the vicinity of Lodestone Mountain.
Magnetite occurs primarily as medium to coarse-grained disseminations intergrown with coarse-grained clinopyroxene and hornblende. The grain size of the disseminations is directly proportional to the grain size of the surrounding gangue. Magnetite also forms semimassive to massive lenses or vein-like bodies, with minor mica and pyroxene, up to 0.6 metres in diameter. The lenticular masses occur in an ill-defined zone, about 100 metres wide, that trends northwest along the crest of Lodestone Mountain for at least 670 metres.
Drilling up to 1969 has outlined proven reserves of 89,497,800 tonnes grading 15.54 per cent soluble iron and 0.084 per cent vanadium pentoxide in an area 1200 metres long and roughly 270 metres wide over a vertical elevation of 120 metres (Property File - Wright Engineers Ltd., 1970, Section 1, page 4; Canada Mines Handbook 1976-77, page 158). Conversion used to V is 1.7852. This area of proven reserves includes a higher grade core with open pit reserves of 40,800,000 tonnes grading 17.56 per cent soluble iron (Wright Engineers Ltd., 1970, Section 1, page 8). Probable reserves along strike to the northwest and southeast are 116,468,300 tonnes grading 13.91 per cent soluble iron for a cutoff grade of 11 per cent soluble iron (Wright Engineers Ltd., 1970, Section 1, page 5). Inferred reserves are estimated at 159 million tonnes of at least 10 per cent soluble iron (Wright Engineers Ltd., 1970, Section 1, page 5).
A bulk sample taken in 1969 contained 22.3 per cent soluble iron and 2.11 per cent titanium dioxide (Wright Engineers Ltd,, 1970, Section 3, page 3). The chief titanium-bearing mineral is ilmenite, with minor leucoxene and trace spinel. These minerals are intimately associated with the magnetite. Additional sampling indicated that titanium is the only impurity to occur in elevated quantities.
Anomalous platinum values have been reported. Samples from three holes drilled in 1966 assayed 0.17 to 1.4 grams per tonne platinum (Imperial Metals and Power Corporation, 1968, assay certificate).
This deposit has been extensively explored by Imperial Metals Corporation. The company drilled 62 holes totalling 3633 metres between 1962 and 1969, in addition to bulk sampling and metallurgical studies. The company had planned to use the magnetite and nearby coal and limestone deposits to produce metallized iron ore pellets. Imperial Metals and Tiffany Resources Inc. have also conducted soil and rock sampling, geological mapping and 1226 metres of diamond drilling in 10 holes between 1986 and 1990, in order to assess the deposit for its chromite and platinum potential.
From 1954 to I955, United States Steel Corporation conducted a dip-needle survey and carried out an exploration program of drilling and trenching. The data from this work is not recorded.
From 1962 to 1970, Imperial Metals and Power Limited conducted a series of exploration programs on the property. Iinperial Metals completed a ground magnetometer survey, trenching, and a total of 3535.5 metres of drilling in 60 holes. The majority of the drilling was done with a percussion machine on a drill pattern of 400 foot centers, on lines spaced 800 feet apart. Much of the specific data from these exploration programs is no longer available, and the location of drill core and percussion cuttings is unknown.
In 1969, Imperial Metals and Power commissioned Wright Engineers Ltd. to conduct a preliminary feasibility study. The prefeasibility study investigated mining iron at Lodestone Mountain, and coal at a nearby location. In 1973, Dominion Foundries and Steel Ltd. (Dofasco) optioned the Lodestone property from Imperial Metals. Dofasco completed nine diamond drill holes and 17 percussion holes for a total of 3219 metres of drilling. In 1984, Imperial Metals Corporation began to evaluate the platinum group element potential of the property. In 1986, the property was re-mapped and prospected. In 1987, Imperial Metals undertook a program of soil geochemistry. Sixty three kilometres of grid line were established and 1,221 soil samples were collected.
In 1989, Tiffany Resources Inc. entered into an option agreement with Imperial Metals Six diamond drill holes totalling 612.7 metres were drilled by Tiffmy and the drill core was analyzed for platinum group elements. No platinum group anomalies were detected in the drill core. In 1990, an additional four diamond drill holes totalling 613.0 metres were completed by Tiffany. These drill holes also targeted the area of anomalous PGEs in soil. In 1993, PBK Engineering Ltd was contracted by Tiffany Resources and Prime Resources Group to complete a preliminary evaluation of the Lodestone iron deposit. The PBK report was based on the 1970 Wright Engineering work.
In 2003, Sargold Resource Corp optioned the Lodestone property from 21st Century Energy Corp. Sargold drilled 1069 metres in 15 holes. All 15 holes of the were reported to have encountered medium to coarse grained magnetite-bearing hornblende clinopyroxenite throughout their length. Good core recoveries were achieved, only two holes returned recoveries below 90%. Visual estimates of magnetite content ranged from 10 to 25%, with occasional short sections of up to 50 per cent. No significant amounts of pyrite or pyrrhotite were noted in the clinopyroxenite. A revised resource calculation compliant with National Instrument 43-101 given as 2,835,000 tonnes grading 24.33 per cent magnetite was defined by the drilling program (Assessment Report 27520). The resource is reported to be in the measured mineral resource category based on the close drill hole spacing, the relatively uniform distribution of the magnetite within the clinopyroxenite and the much larger, surrounding extent of similar mineralization encountered in historic drilling.