| Francon Quarry - St. Michel, Quebec |
 The Francon quarry located in St. Michel on the Island of Montreal, has become a world famous minerals collection site. While Mont St. Hilaire is well known for the number of mineral species it yields, the fame of the Francon site comes from the fact that six yet unseen minerals were discovered at this location - weloganite, dresserite, hydrodresserite, strontiodresserite, franconite and sabinaite. You will find a description of these minerals under their own heading. The formation of the Francon site comes from the same underground igneous activity that produced Mont St. Hilaire, i.e. the penetration of magma into the Ordovician limestone. In fact, three separate sills (melted rock that horizontally penetrated the surrounding pre-existing limestone) are found in the quarry. However, it is only in the two upper sills exposed by the quarry operations that one finds minerals of real interest. One might then ask, if these two sites are related in their origin, why does one quarry have so many different species (in the hundreds), while the other has considerably less, but yet contains brand new minerals? Although the melted magma that penetrated the Francon location also has an alkali origin (as with Mont St. Hilaire), the rock type found there is known as a silicocarbonatite. The composition of a carbonitite is similar to limestone (i.e. calcite and dolomite), but it has an igneous origin. The silico prefix is added to the carbonitite because of its contamination from a melt of silicic origin. This contamination is evidenced by a large amount of sodium from the common mineral feldspar as well as its "higher than normal amounts of zirconium and niobium." |
Mont St-Hilaire
Francon