Industrial mineral potential in the Appalachians
The Appalachian orogenic belt in Québec
offers great potential for asbestos (chrysotile),
talc, steatite (soapstone), high-purity
limestone, silica, peat
and salt. It also hosts a few undeveloped
deposits of barite, chromite and
chrysotile orebodies associated with the ophiolite
zone in the Appalachians of southwestern Québec (Estrie and
Beauce regions) were once mined in the late 19th century
and throughout the 20th century. This ophiolite
zone lies along the Baie Verte- Brompton Line, a regional-scale
intense deformation corridor. Numerous talc and
steatite deposits associated with this zone have
also been mined in the past. However, the only talc operation in
Québec, located near Saint-Pierre-de-Broughton, shut down
in 2001 due to the presence of asbestos fibres in the ore. Nevertheless,
steatite is still being extracted at the Fraser mine near East-Broughton.
In the Appalachians of Québec, limestones
are quarried in the Lake Champlain area (Missisquoi Bay) south of
Saint-Jean-sur-Richelieu, and in Lime Ridge northeast of Sherbrooke.
Other potential sources of pure limestone were identified in the
Bas-Saint-Laurent region and in eastern Québec, in the Gaspésie
region. In the Lake Champlain area, mined limestones are part of
the Corey and Strites Pond formations (Philipsburg Group). In Lime
Ridge, where lime production has been going on for over 150 years,
quarries operated by Graymont Inc. are located in a very pure, partly
recrystallized reef limestone. In the Bas-Saint-Laurent region,
limestones of the Témiscouata, Sayabec, Rivière-Ouelle
and Romieu formations offer good potential for industrial stone
purposes. Argillites of the L’Orignal Formation in Lepage
Township (Mont-Joli area) were once extracted to manufacture clay
products. An obsidian deposit occurs in the easternmost part of
the region, in the Mont Tuzo and Mont Squaw Cap area. In the Gaspésie
region, important deposits of pure limestone associated with the
West Point and de la Vieille formations (Chaleur Group) were identified
in Lefrançois Township south of Rivière-Madeleine,
as well as in the Port-Daniel area south of Baie des Chaleurs.
the Bas-Saint-Laurent and Gaspésie regions, quartz-rich
sandstones of the Val-Brillant and Kamouraska formations
have a silica content greater than 96%, and constitute potential
sources of silica. These two sandstone units have been mined in
the past as a source of siliceous flux.
The Bas-Saint-Laurent region plays a major role
in Québec’s peat industry. There are at least twenty
peat deposits in the region, primarily located along the fleuve Saint-Laurent. Production figures for the region represent 50% of the total
peat output in Québec. Most of the harvested peat is shipped
to some forty different countries.
The Permo-Carboniferous basin of the Appalachians
(Magdalen Basin) hosts salt and gypsum
deposits and also constitutes a source of silica sand.
Seven important salt deposits, some with interesting potassium grades,
were discovered in the bedrock of the Îles-de-la-Madeleine,
at depths ranging from 30 to 300 metres. The most important, the
Rocher-au-Dauphin orebody, has been mined since 1982 by Mines Seleine
Dunes and tombolos on the Îles-de-la-Madeleine,
along with part of the continental platform along the eastern margin
of the archipelago, consist of silica sand, essentially
derived from sandstones. This sand deposit, located in the Sandy
Hook channel between Île-d’Entrée and Île-du-Havre-Aubert
has been evaluated as a source of silica sand for smelting and glass.
This sand contains a significant proportion of feldspar however,
which must be removed.
Sedimentary basins in the Appalachian orogenic
belt host a few barite deposits. The Upton orebody
(Robex), associated with the Upton Group, and the Saint-Fabien deposit
located in the Saint-Damase Formation (Trois-Pistoles Group) are
currently the two largest known barite deposits in Québec.
They have not been the object of mining operations however.
Ophiolitic complexes in the Appalachians (Thetford
Mines, Asbestos and Orford area) host numerous podiform chromite
deposits. The latter are hosted in dunite lenses within tectonized
harzburgites, and in dunite horizons within cumulate sequences overlying
the harzburgite. Several of these deposits were mined during the
two world wars.
The main gypsum deposits occur
as 5 cm to 5 m beds in a breccia with mudstone and sandstone fragments
of the Maisons Formation (Windsor Group). Tiphane (1970) estimates
at some 100,000 tonnes the amount of good-quality gypsum that could
be easily extracted from the bedrock of the Îles-de-la-Madeleine.
Outlook and Opportunities
complex in the Appalachian orogenic belt of southwestern Québec
constitutes a prospective geological setting for the discovery of
new chrysotile asbestos, talc and steatite deposits. Sedimentary
basins in the Appalachians, on the other hand, offer good potential
for industrial stone (limestone, silica) and for salt and gypsum