What role do you think a Polybasite would play on Homeworld? I was thinking something like an assassin because they contain arsenic and arsenic was used as an assassination weapon but I'm not too sure since they're rather low on the Mohs scale and seem like they'd be too easily damaged.
I looked up polybasite on a few websites and it looks like they’re more rich in antimony than arsenic (their mineral “relative” pearceite is more arsenic). Arsenic can be found in them, but generally not. You’re correct that they’re a bit too fragile to be assassins (their MOHS scale hardness is 2 ½ to 3), but you can make the argument that speed and precision is all really an assassin needs. They don’t need to be super tough, they just have to be fast and sneaky enough to do the job right. And to be fair, a lot of arsenic minerals are very weak. Then again polybasite is an uncommon mineral and Homeworld probably wouldn’t waste their resources on a weak assassin species.But I think we can make it work: antimony can still be deadly. Maybe they aren’t assassins, but maybe they’re brought to planets with life to kill off any pests that get in the way of gem colony construction. They can be paired off with a pearceite and left to take out whatever’s been causing the problem: perhaps through a mist or aura they give off. They could fight too, but their specialty would to give off enough toxicity to kill off whatever they needed to kill. If you still want an arsenic assiassin, here are some more durable and more common minerals and gems to choose from: malachite (it’s poisonous when put in water), arsenopyrite, cinnabar, orpiment, and galena.