Sounds like “vegetable ivory” (tagua nuts) can be found as large as a tennis ball or a medium/large avocado shape, but hollow in the core, about the size of a small avocado seed. And so, probably “iffy” for pipes unless luck would put the hollow area in just the right place (for the larger parts).
http://www.oneworldprojects.com/products/tag_raw.shtml (pics of harvest and X-sections)
Another informative site:
http://www.cuillinn.com/ivory.html
Includes price for ivory or mammoth upgrade on pipes, legal issues, walrus ivory, etc. Here’s a few quotes…
“Yes it is a touchy subject, politically, ethically, and environmentally; and yes, it is available through legal sources, with full documentation as to origin and date of 'harvesting.”
“Legal elephant ivory is terribly expensive, but, if you have a set of pipes with damaged ivory mounts that need replacement, we can do it.”
“A full set of projecting mounts, buttons, chanter ball, drone bushes, and mouthpiece will run about $3,000 to ‘ivory up’ a half-silver set. A complete set of mounts, ferrules, and ringcaps will run about $5000 - plus the cost of the pipes themselves.”
“An alternative material relatively new to bagpipes is MASTODON, or MAMMOTH IVORY, which is a by-product of mining in Russia (vhat are they minink??? Who knew? I mean nu?), and is also found in Alaska. Less expensive than elephant ivory, it is still pricey, but completely LEGAL for export or import into the US, as it is a ‘fossil’ and not an endangered species (I’ll say!). Mastodon ivory is beautiful, and slightly darker than elephant ivory, with an ecru or dark cream colour rather than the near-white of new elephant ivory. It has the same appearance when turned through the ‘eye,’ or center of the tusk, with the distinctive interlacing or ‘lamellae’ characteristic to pachyderm tusks. I’ve worked this material myself, and it is lovely to turn - and expensive! It’s painful to see all the waste material flying off the turning gouge when you work it, but that’s the nature of the business!”