again to László and Elsy Horváth for taking me
there - nice place to collect ! And naturally - for information and
St.Amable Sill is an
intrusion between the towns of St.Amable and Varennes in Québec,
about 20 km ENE of Montreal (andabout 20 km WNW of Mt.St.Hilaire). It
is related to the Monteregian alkaline rocks, and it is the most
extensive and thickest sill in this complex. The age may be betwenn
80 and 145 million years. The sill, which lays upon a black shale,
has a very distinct contact zone of up to 2,5m. The sill rock can
best be described as a nepheline syenite. Within the sill there are
horizontal zones of mineralized vugs and cavities in the upper
portion, and tiny cavities in the central portion. Rarely there are
pod-like areas rich in vugs and cavities of hydrothermal origin.
Boths types of cavities yield lots of interesting minerals.
The first description
dates from 1942, the first quarrying started in 1959. As in MSH, the
quarrying history is pretty complicated, today mining is done in the
Demix quarry (yes, same company as in MSG until 1981) in a flat open
pit of about 1,5x0,9 km. Peter Tarassoff was the first to discover
unusual minerals in cavitis in 1962. In 1991 the authors mentioned
below started a comprehensive study of the St.Amable-Sill.
- Amphibole grp.
- Chlorite grp.
- Kaolinite grp.
- Smectite grp.
- VUK1 (silicate)
- VUK3 (oxid/hydroxide)
- VUK6 (silicate)
- VUK7 (silicate)
- VUK8 (silicate)
- VUK9 (silicate)
- VUK11 (carbonate)
E.Pfenninger-Horváth, R.A.Gault, P.Tarassoff: Mineralogy of
the Saint-Amable Sill, Varennes and Saint-Amable, Québec. The
Mineralogical Record, 29(1998), 3, 83-117