Jeffrey Mine, Val-des-Sources, Les Sources RCM, Estrie, Québec, Canadai

Regional Level Types
Jeffrey Mine	Open-Cast Mine (Inactive)
Val-des-Sources	Town
Les Sources RCM	Regional County Municipality
Estrie	Administrative Region
Québec	Province
Canada	Country

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Formerly: Jeffrey mine (Johns-Manville Mine), Asbestos, Les Sources RCM, Estrie, Québec, Canada.

Formerly: Jeffrey mine (Johns-Manville Mine), Asbestos, Asbestos RCM, Estrie, Québec, Canada.

Formerly: Jeffrey mine (Johns-Manville Mine), Asbestos, Shipton Township, Richmond Co., Québec, Canada.

The town voted to change the name from "Asbestos" to "Val-des-Sources" in October 2020.

"Jeffrey quarry" in earlier locality strings has no trace in the literature and should not be propagated. The "Johns-Manville mine" is also a misused name, as it was not officially used; Johns-Manville was the corporate owner and operator of the mine for most of its history.

Mine: Open-pit chrysotile asbestos mine, measuring some 2 km in diameter and eventually reaching a depth of 350 m. Mining began in 1879. In 1950 an attempt was made to switch to block caving, but this method was abandoned after 10 years. In 1969 the pit was expanded, requiring the relocation of the adjacent town. However, world demand for asbestos fell drastically in the 1980s when its carcinogenic properties became known and worldwide bans were implemented on its use as a building material. In 1996, in an attempt to mine a high-grade area at the bottom of the pit, another attempt was made to switch to underground methods, but government subsidies were exhausted in 2001, and since then the mine has been inactive.

Regional Geology: While the ultramafics of the Thetford-Ham area are a typical ophiolite complex, their origin remains controversial. "Ophiolite" is a term referring to an assemblage of ultramafic and mafic intrusive and extrusive rocks, widely believed to represent oceanic crust. Such complexes are characteristic of many orogenic fold mountain chains and are sometimes preserved when an island arc system is scraped off of one tectonic plate as it collides with and is subducted under another plate, creating fold mountains. However, others have concluded that the ultramafic rocks of southern Quebec and Vermont are not oceanic crust remnants because many are intrusive, with peridotite the most common. Furthermore, Precambrian outcrops in the area appear to be continental, not oceanic, crust. They suggest instead that the ultramafic rocks are from the upper mantle, emplaced as solid intrusions during deformation of the Appalachians. Still others propose that perhaps the Quebec ultramafic rocks represent gigantic submarine extrusions or feeder conduits for submarine eruptions.



The geological map is copied from Horváth et al. (2013)

Local Geology: The Serpentine Tectonic Belt of the Lower Ordovician rocks of the Appalachians comprises serpentinized dunite, chromitite, pyroxenite and peridotite, all intruded by diorite, syenite, granite, gabbro and ultramafic to intermediate volcanic rocks. The dunite and peridotite that are associated with the asbestos deposits were heavily serpentinized in successive stages soon after crystallization, especially where sheared and intruded by granitic to dioritic masses. In a later phase of serpentinization, shear zones and fractures channelled the asbestos-forming solutions. Later dike intrusions into the dunite and peridotite formed irregularly, and, as at the diorite contact zone with the serpentinized zones, they tended to facilitate replacement mineralization. Calcium- and aluminium-rich fluids were deposited in joints and shears in the diorites and ultramafics, and occasionally were intruded as discrete dikes called rodingites.

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.

Mineral List

113 valid minerals. 4 (TL) - type locality of valid minerals.

Rock Types Recorded