What can you do with sturdy quartzite and sturdy marble shards?

[goatgas]

I have some but don't see how they are used, unless its tied to some chip?

[pcdeltalink]

Once your weapons and armor are upgraded past a certain lvl they will require higher tier upgrade materials. Sturdy quartzite and marble come into play then.

[Eisvogel]

Hey man! You should be able to use them in workbench. I don't recall if they are analyzed, check just in case but i think they didn't require analysis.
They are used for upgrading your equipment (quartzite for weapons, marble for armor). You only need some early game progress (up until you meet BURG.L in oak Lab) and you can unlock the smithing station recipe for only 100 raw science if i recall correctly

[Catpuppy]

You start getting the sturdy variants generally a lot earlier than you can actually use them, since creating them into the next upgrade material requires an Oven.