Where can I find more brittle marble/quartz?

[StretchyStretch]

I've looked in the Red Ant Hill and apparently cleaned it out. Does more ever respawn? And is there another place to get them?

[Tyz]

As far as I've noticed, the nodes do not respawn however there is an unholy amount of brittle all around the map. You'll find more in no time, just make sure to thoroughly explore caves and weird nooks.

[Jack]

They don't respawn. The higher tiers of quartz and marble also contain brittle fragments though and once you get further into the story you can get recipes to make the upgrades from resources that do respawn