Welcome to Coticule.be.
As been said, it's not possible to determine the whereabouts of old Coticules, because we have no way of knowing from which mine they were extracted, and even if we did, there is no information about the layer morphology at the abandoned mining sites.
But we can talk a bit about your lovely collection.
What strikes me about the one you called Robert, is that it shares several features of the La Dressante layer at Ardennes' Ol Preu quarry.
There is usually a slightly darker band of Coticule, adjacent to the BBW, that changes with a usually straight line to a more pale band of Coticule. Nowadays, they usually make the cut at that straight line, and sell the slightly darker Coticule as "La Dressante au Bleu". The paler slice is than glued to slate and sold as "La Dressante Upper Layer". They do differ in properties somewhat. The upper layer is usually faster, certainly when it caries faint black manganese lines (as your "Robert" does). I can't confirm. hat it really is La Dressante, but those are at least some interesting resemblances.
Then we have "Raymunda" with its very distinct pale, almost white color. To my knowledge, there were only very few layers that delivered Coticules that pale: the fabled "Vieille Roche - Old Rock" layer, from the mine and company with the same name, and the La Veinette layer, often rebranded as "Old Rock". In the old days, Coticules were sold in a multitude of different grades, and white uniform Coticules were definitely in the most expensive grade. There's a decent chance that "Raymunda" is an Old Rock, but again, I can't confirm anything.
Kind regards,
Bart.