I'm currently in the process of working through the last of our larger-sized blocks of Breton morta. I've got plenty of small blocks, but they're good for thimble-size bowls only - The last of the bigger bowls will be turning into pipes through the rest of this summer, most likely (And I should add, I'm not taking any orders for any of these - I'm just going to play with them and make the best shapes I can from them and post them to the site as they're completed. Most of the blocks are not suited for the traditional shapes folks like to request, anyway). This spurred me to write a quick post about morta and how to judge it, because even more so than briar, it comes in good and bad quality. Here's a block that showcases the bipolar nature of the stuff, with the opaque black portion being some of the best quality of morta that one can get, and the ragged brownish part being unusably sub-standard (Click the pic for a larger view).
The bulk of the block is excellent - Extremely hard, fully mineralized, resistant to blasting and burning, and ideal for pipemaking with a rich, dusky flavor that enhances darker tobaccos. The right-hand section was not, in effect, fully "cured" by time - It's still partially fossilized but it's much softer and lighter than the black stuff, as can be seen from the surface. The entire face of this block was sandblasted equally, and it's clear which portion is most dense and where the weaker part is. While this can be used for pipes, I don't - I prefer the denser material by far. It's noticeably heavier and most importantly, naturally black. I've heard of some of the morta on the market needing to be stained black... Folks, that's just not good. Brown morta, from what I have personally experienced, cut and cured, is softer morta, not ready to become a pipe. The wood isn't sufficiently fossilized to resist flame as well, and it has a woodier taste to it. My personal opinion is that if it has to be stained, it's better not to use it.
I'm still looking for reliable sources for good quality morta to use in future - We'll see how it goes. In a strange way, I'll probably miss these tiny little blocks when they're all gone, since by their very size, they force one to be extra-creative in trying to wring a decent looking pipe from them.