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Petite vs Grosse


Well-Known Member
Howdy all,

I've been reading through the forums and have found a wealth of knowledge on pretty much anything under the sun.

One question I have tho is why are some layers called petite and grosse but have the same ending such as blanche?

I know they must be somehow similar but I can't find the thing that makes then so. Based on some pictures of the Ardennes mine that Bart posted they don't even seem to be in close contanct which could be an explanation for the names.

Maybe I'm just over thinking all of this but it would be interesting to know what the connections might be.


Well-Known Member
I think the answer is rather simple. "Grosse" means thick, large. "Petite" means small. La Grosse Blanche is a relatively thick layer of which each fragment can be cut into 2, 3 or even 4 Coticule slices. For that reason, most La Grosse Blanches are glued to slate.
La Petite Blanche on the other hand, is a narrow layer. It holds only one stone. That's why La Petite Blanches nearly always are bonded to their natural blue counterpart. The name Blanche (means "white") refers to the pale and even color of both layers. La Grosse Blanche turns brown when exposed to (sun)light for a prolongued time, but in its non-oxidized state it is just as La Petite Blanche, typically of a pale creamy color, without any special color hues that are sometimes seen in other layers. (Manganese lines do occur though)

So, basically we have the "Beefy Pale Vein" and the "Skinny Pale Veine".

Kind regards,


Well-Known Member
Thanks for the reply Bart.

I would have never figured that the answer was so simple!

Now I feel silly for asking. But I guess there are no stupid questions.