Some hickory heartwood I've seen is pinkish, but it could also be that it was infected with a mold that weakened it. And then some particular pieces I've used were just more brittle than the average for whatever reason. I tend to find an older tree to have more brittle wood than a younger tree, that based on some limited observations of course. My favorite trees are 8-12" diameter, skinny enough that each ring has seen a substantial amount of stress during the growing season. Those older trees, the outer rings tend to be thinner and I thin the latrge amount of wood in the interior may be protecting the newer wood from being strengthened by periodic stress from wind etc.
