shaking my head around like a wolf with a rabbit ive gotten really back into my houseki ocs recently. in order of appearance: cassiterite, purple diamond, ulexite, chalchotrichite.
on this island, one of the big differences is that they also use archers extensively, like cass. being an ore mineral (in this case, a gem with native ore running through their body like phos's alloy) makes you taller, so you have the ability to draw taller bows, and provides tensile strength that gems generally don't have. cass was picked as an archer virtually at birth which gives them some complicated feelings surrounding it.
purple diamond is the island's only diamond and has already lost two partners because of it. no one else can keep up with them. they play at being a star, but they're terrified of losing another.
ulexite is also called tv stone in real life! because it has natural fiber optic properties, so if you put a polished block of ulexite on top of a piece of paper, you can read through it. because of their very low specific gravity they're exceptionally quick, but they wear a headscarf to make it easier for the archers to see where exactly their (otherwise very difficult to see) head is. they're one of the island's most seasoned lookouts.