The geology of and product applications for the Penhorwood Talc Mine, Penhorwood, Ontario, Canada

摘要

The ore body of the Penhorwood Mine in Reeves Township, 74 km west of Timmins, Ontario is the largest talc mining operation in Canada. This open pit deposit was first developed by Johns Mansville in 1974, but was shortly sold to Steetley Talc in 1978. The mine, flotation plant and the Timmins micronizing plant have all been owned and operated by Luzenac Inc. since 1988. The annual production from this mine is currently at 230,000 short tons of talc magnesite ore, which feeds the adjacent flotation plant on the Penhorwood mine site. The origin of this type of serpentinite- hosted ore body is related to the eruption and emplacement of extrusive dunitic komatiitic magmas within the Archean Abitibi Subprovince in a probable island arc tectonic environment. Magmatic segregation within these magmas produced layered dunite and peridotite lithologies, which were later serpentinized as they were cooling. Magnetite formed as the prevalent opaque mineral and crystallized during the serpentinization process. Secondary carbonatization of the serpentinites, as a result of carbon dioxide metasomatism radiating out from major structural fault intersections, formed the talc magnesite mineralogy. Aluminous zones were altered to chlorite, and areas of intense carbonate alteration resulted in the conversion of the magnetite to hematite. This deposit does not display the typical blackwall alteration due to the lack of quartz- feldspar- mica country rock and the outward alteration pattern into the serpentinite on the margins of the talc carbonate body. For almost 30 years high quality floated talc concentrates and micronized finished products have been generated from the Penhorwood and Timmins operations. Due to the platiness and whiteness of the Penhorwood talc, the products perform extremely well in specialty ceramic, polymer and coatings applications. Products are shipped throughout North America from the Ontario production facilities.