There are various ways for obtaining Quicksilver (short QS)... Either by "intention" or, well, by accident.
How to get Quicksilver:
-The "prime" way is to exchange resources obtained from Superbeings. NPC that does this kind of exchange is Gredeya the Witch for Humans, and Brugilda the Sorceress for Magmars (The more colorful your Juggernaut medal is the more QS you'll get by exchanging resources).
-There are two events that also give resources that can be exchanged in the same way.
1) Green Pirates event, located on the ship to County Vurdaliya for Humans or Virigiya District for Magmars. The event's objective is to pick tentacles from the sea in the hunting screen. Each tentacle brought to previously mentioned NPC will provide a certain amount of QS (~10, but not sure).
2) Uborg's Wrath event, located in Wastelands of Rest for Humans and Eclipse Thicket for Magmars. The objective is the same as in Green Pirates: pick tentacles. A set of 10 tentacles will provide certain amount of QS (~10, but not sure).
-Exploring lights on Graveyard Lights event may drop 2 pcs of QS.
-Chests from Capture the Contraband (Dead Cove for Humans and Barrow of Death for Magmars) and Dangerous Guests (Virigiya District for Humans and County Vurdaliya for Magmars) events can provide QS. (~5 pcs, not sure).
-Magic of the Stone event (Gryphon Crossing for Humans and Wyvern Crossing for Magmars): by cracking granites you can find QS (5 pcs).
-Having reached 1000 influence in Caves of Fear you will receive QS (30 pcs).
-Magic Wand can also drop QS (10 pcs).
-QS can be found in the stashes on Plateau of Silence, Haunted Place, Kretch Lair's Patriarch Cave, Derelict Houst, Magish's Palace, Bog Elf swamp, Ship's Graveyard (I'm not 100% sure if the last 3 stashes can give QS).
-By playing daily Gift of Heaven dice game you can receive 5 pcs of QS.
-While opening Gnome Caskets you can receive QS (the better the casket the more QS you'll receive).
-Dropping coins during Luck Glow event can provide you with QS (30 pcs).
-During special promotions you can buy QS for gold/diamonds.
-A machine called 'Quicksilver still Breeze' will provide QS on a daily basis. It is can be bought from Fortune Hunters shop after receiving 500 reputation standing. Every medal stage of this reputation will open new blueprint for the machine's improvement, which means that it will give more QS every day.
What is Quicksilver used for:
-Activating Gnome Runes:
QS required to activate depends on rune's color:
Gray - 30 QS
Green - 120 QS
Blue - 330 QS
Purple - 930 QS
Red - 2700 QS
-QS is used in 4th part of Clan Upgrade (a total of 3000 QS needed - 100 for each certificate and 30 of them are required).
-In making Mercury Mirror you will need 48 QS.
-Finishing some quests.