Buy RS3 Onyx dust
Onyx dust is fine dust from an onyx gem in RuneScape 3. It is a members item that is tradeable and stackable, and it weighs nothing, so it takes up little space in your bank.
The main use for onyx dust is making an uncut onyx with the Divination skill. You need level 97 Divination, 100 onyx dust, and 250 incandescent energy to transmute it. Each transmute gives 23.4 Divination experience. This cannot be assisted by another player.
Onyx dust drops from strong bosses like Raksha, Arch-Glacor, Croesus, TzKal-Zuk, Hermod, and Rasial. It also drops from bosses in the elite dungeons, such as Seiryu the Azure Serpent and the Black stone dragon. Common monsters in the Temple of Aminishi, Dragonkin Laboratory, and Shadow Reef can drop it too when you use a lucky charm. Other sources include metamorphic geodes, ancient caskets, and Hero Satchels.
Onyx dust can also be disassembled for Invention. It gives Simple parts most of the time and Variable components on rare tries. Players want onyx dust for Divination training and for turning stacks of dust into valuable uncut onyx gems.