Blue River Area

North and northeast of the town of Blue River several sheets of carbonatite have been delineated which are conformable, and commonly sheared and boudinaged. Some workers have considered these to be metamorphosed limestones, but Mariano (personal communication, 1985) points out that all the occurrences are in contact with syenites and other alkaline rocks, and that their mineralogy and geochemistry indicate that they are carbonatitic. The main group of occurrences lies just south of Lempriere and includes the Verity, Mill, Paradise, Fir and Bone Creek claims; the first of these is described in the next entry (031-00-025). The Howard Creek occurrence lies a few kilometres to the east and the Mud Lake carbonatite to the south, just northeast of Blue River.
Howard Creek includes several isolated carbonatite sills and bodies of ijolite-urtite, a sphene-rich amphibolite (called 'lemprierite' by A.N. Mariano and J.A. Gower - Mariano, personal communication, 1985) and koswite (?magnetite peridotite or pyroxenite). The Mud Lake carbonatite contains pyrochlore rich in Ta. The Fir claims consist of several beforsite units about 30 m thick. Mariano (personal communication, 1985) says further lenses of carbonatite are being found all along the Monashee Mountain Range and on the west side of the North Thompson River. They all have accessory pyrochlore rich in Ta.