Legend to the sketch above: Couches à Cératites -
Ceratite beds; Couches
à Entroques - ossicle limestone; Dolomie - Dolomite; Marnes
bariolées - checkered Marls; Grès à Voltzia -
Voltzia sandstone; Grès intermédiaire - Middle
Bunter; Champs - Fields; Bois - Forest; Vignes - Vineyards; grande
carrière - big quarry; Quartzites du Dévonien - Devonian
Quartzites
Sierck-les-Bains is a small town
in the river Mosel valley, situated on the French side of the
"three-country-corner", facing directly the villages of Schengen in
Luxembourg and Perl in Germany.
The barrier of Sierck is
located at the southern rim of the Hunsrück
mountains, marks the northern limit of the Sarro-Lorraine coal basin and
reaches into the south-eastern tip of Luxembourg, where it exposes Lower Devonian Quartzites in the
river Mosel valley, after the river having cut through covering
Triassic beds composed of Ceratite and ossicle limestones, Voltzia
sandstone and Dolomite, which had been exploited during the last
century for the local iron industry.
Due to this very disturbed
facies it may certainly be assumed that this barrier had been
reactivated during the Upper Muschelkalk.
These Quartzites are splitting into several meter-sized sequences whose
major parts consist of sandstones overlayn by more micaceous rocks. The
entire assembly being intersected by mineralised veins of milky quartz
occurring in crevices of the alpine type.
Quite a number of quarries can be found,
formerly exploited for most diverse purposes.
Indeed, Quartz veins were use in
fayence industry, for the production of millstones; crushed
sandy Quartzites for graveling railways and paving streets in the
cities of Paris, Nancy and Metz. Micaceous Quartzites cut into slabs
were used for paving small ways and gardens.
Still today large quantities of Chlorite-
and Hematite-containing Quartz crystals, several centimetres in
size, can be found. Micro-minerals
also can be found, like Goethite
and Hematite in small geodes of hyaline Quartz.
Several
groups
of Quartz crystals typical for Sierck-les-Bains:
(click onto the photos to
increase them in a separate window)
It
should not be necessary to remind that each search requires the previous
authorisation of the landowners, be they municipality, industry
or individuals.
It should be noted, too, that the nearby
valley of Montenach is classified "natural reserve".
Text, sketch, minerals:
Stéphane Hassler,
Sierck-les-Bains; photos: J.C. Pitsch
