From Dark and Darker Wiki
Rubysilver
There is currently only one mineable material which is Rubysilver Ore. These ores can be extracted from Rubysilver Nodes located throughout the various maps. Rubysilver Nodes can be mined by equipping a Pickaxe from your quickslots. It will take you multiple cycles of mining until you're able to break them to harvest the ores.
These can then be converted via the Services option to either Rubysilver Powder at the Alchemist or Rubysilver Ingot at the Weaponsmith. Crafting these will cost 6 and 10 Rubysilver Ores respectively. After you have a sufficient amount of materials, you will be able to craft the armor of your choice. (Currently there is no option to craft any weapons with this ore.) Rubysilver Ingot is used in Heavy Armor and Rubysilver Dust is used in Leather and Light Armor crafts.
Tips
Hitting nodes with multiple people will not affect the time it takes for nodes to break and only one person will receive 4-5 Rubysilver Ores.
Your character will be extremely vulnerable during this process, so it is best to get to cover and clear the rooms before attempting to mine.