~Rare Ore usually a common drop from most of the monster in Rf Online.
~It cannot be sold to any NPCs, however it is tradable with other, so you can trade it with other players.
~You can change Rare Ore into a better quality ore by collecting 5 Rare Ore and exchange it for 1  but every process from Rare Ore into  Requires a few of your race currency.
~You can Trade These beautiful processed Rare Ore for a gift box from "Gem Collector" which just nearby "Ore" Npc.
-The gift box is divided into 3:
=>Master's Small Gift.
=>Master's Large Gift. ---> Most of the people says that this is the best cheapest way to obtain a relic weapon without spending over Millions and million of your race currency, but that was if you're lucky enough to get that.You can also obtain Talic, +4 ores (maybe), Weapons, or unfortunate enough an empty large box.
(P/s:This depend on your processed stone,the better the quality will grant you a Master's Large Gift.)
~Feeling down because you a lot of Empty Large Box? No worry, There's a good deal to it. Collect 50 (if i'm not mistaken) of those Empty Large Box and go to the "Gem Collector" once again and choose "Recycle box trade".This box is rumored to have the best chances out of all Master's Gift box.
Hope this helps ^-^
However, sorry that I don't know that much about this game but this is the far best that I can do.