Monday, August 18th, I'm going with Vintz friend of Castre, visit Pans Travassac a slate.

Open to the public since 1997, this is the first site of 'industrial tourism', to discover the work of slate. Mention is made of slate Travassac deposit since 1616 (part of which was owned by the Knights of Malta) and the creation of the Company Ardoisières Corrèze in 1849 by the family Jouvenel. (Here, the jump of the shepherdess, 140m high, much of it under water:)

In XVI - XVII century, slate stone used to build, and by the properties of the rock (waterproof, thin and flat), it replaces the thatched roofs (significantly adding to the weight of the roof anyway!).

The pieces of slate have 7 Travassac veins each appointed by the slate and up to 140m deep. The point of the measure Fayotte 100m, 75 underwater (because of the rain, slate being sealed, the water can not escape, the slate were forced to pump water continuously in order to continue exploit the seam).

Slate is a sedimentary rock (bottom of the ocean for example) horizontal. She stands up vertically because of extensive tectonic (not the thing that wants to be a dance, I talk about the geological term from drifting continent and the work of so-called tectonic plates together, exerting colossal forces). But the slate can not be homogeneous ('clean') quartz veins can form in the plates in which microcracks, with the hardest time and strength of quartz, the slate by Click to enlarge and to be filled by quartz again, distorting the cleavage of the cap. A slate with quartz can not be used for the roof due to the brittleness caused.

Between the veins of slate digging breakthroughs to transport slate from a vein in the other (the orange color is due to the presence of iron oxide):

Upon entering the first vein, adjacent to the jump of the shepherdess, we go on a metal bridge over water (there is a lot of depth, and width of about 8 to 10 meters, the people prone to claustrophobia may feel uncomfortable, oppressed).

A new breakthrough brings us to the next seam, where the guide explains how the slate are charged more than one tonne blocks: the paroies are dug boreholes up to 1m deep, with an angle between 10 ° and 20 ° relative to the plane of the cliff, and forming acute angle. At the bottom of this hole is packed a load of gunpowder (not dynamite, the explosion is too dry, it would reduce the slab millions of completely unusable pieces) to take off the huge plate of pan. The explosions may, from time to time make kinds of original sculptures (a snail and a butterfly for example):

As we go up the seam, the guide explains that the site had its heyday around 1900 and had between 200 and 250 employees at the end of the Second World War, with the discovery of asbestos cement and composite materials, the slate has begun to decline, like all slate.

A breakthrough brings us above the previous gateway to the view (we see where we entered the veins)

Leaving the vein, we come to the place of size, antique, with huts of slate:

There the guide goes out to the slate for the explanations and demonstrations of size. He explains that there is now more than 4 slate on the site, and that it did not close due to the very top quality slate therein (a lower porosity 2%, producing a (much better than the slates from China) very smooth fine slate base). The stone is of excellent quality, but capricious, for it to be good, it has to sound a certain way when the tape, like a bell. Because of that, the reject rate is 80%! discharges are either brittle or have a bad sound. Waste can be used to get accurate pricing of low-end design, or driveways into small pieces. The most beautiful songs (not so waste) are used for roofing.

The slate roof are cut in different ways depending on the thickness that the tailor can draw: fines (3 - 4 mm thick), they are mostly rectangular; strong (13 - 15mm thick) will be mainly carved arched. But before we get there, the slate shall deduct from the block a ton (the Reballing), then repantons and finally cleavage to obtain sheets (thin or heavy). In a working day, a slate can get between 600 and 700 slates.

The slate size sheets according to customer demand, now and for many years a very important customer ordered 1'500m² slate and has added yet 1'400m² ... to renovate roofs of all the Mont-Saint-Michel! The slate measures 25 x 20 cm and 15 to 22mm thick, rectangular.
But be aware that the installation of the slate does not 'butt' to ensure a good seal, you must make a recovery ... where a normal tile merely a collection of 30 50%, the application slate 66.67%: where the upper tier is fixed nail (copper or stainless steel does not corrode) is called 'recovery' (covered by two layers of slate), the central tier called 'false-gauge' (coated thick slate) and finally the lower tier is called 'the gauge', it is outdoors. The slates are laid in a horizontal line as overlapping each other, and to seal the slot recouvrire left between the two slate below. Ultimately, this recovery system protects the roof infiltration, but is heavy between 30 and 35 kg / m² for fine slates and between 50 and 55 kg / m² for high slates. Built to last (more than 1,000 years without anything moving, so fixed), the slates are here one of the best quality in the world ... and like any quality, this comes! Duty-and off-set, then m² slate costs 60 €. But with the installation and taxes, the price rises to € 200!

Following the tour continues with a long descent in another vein, the time to go down the steps, we quickly feel the cold surround us and humidity increase!

Here, under a stone archway in a larger breakthrough is the museum of the slate, with tools used here, pictures, documents going back further in time and a small video report dating from 1968 (for France 3 if I'm not mistaken) telling the workings and history of the slate travassac.

Finally, the output, with small benches and a store dedicated to slate (jewelry, dishes, paintings, sculptures) and some local products (honey Correze, walnut liqueur, violet mustard, etc ...).

To return to the car, we must go on foot by a path along the cliff everything we descended with steps!

Ultimately, this is a site that I recommend to see at least once, and preferably in good weather! They are closed during the cold season and the price is not exorbitant.
Incidentally, above the parking lot at the top, one can pick up a few pieces of slate lying on the ground and that are part of this waste ... slate with a very fine grain, once prepared, can be used to sharpen knives (I personally use it with a piece that I use since 2006 and with a sharpening from time to time, my knife still cut as well, no need to make 50 round trip and you do not end up with a blade teeth saw!).