Fulminated Mercury - Sekiro Shadows Die Twice

Fulminated Mercury
Highly precious grains forming the base for a devastating form of gunpowder. Used in explosive Prosthetic Tool upgrades of advanced rank. Created in secret by the Interior Ministry using knowledge from across southern seas. The central forces' military might owes much to this tiny tweak of chemistry.

Fulminated Mercury (雷汞, Raikō) is a special Upgrade Material in Sekiro: Shadows Die Twice. Fulminated Mercury is required for upgrading explosive Prosthetic Tools, and can be found in specific Locations or looted from specific Enemies.

Fulminated Mercury Usage

• Bring this material to The Sculptor located at the Dilapidated Temple to upgrade the following Prosthetic Tools:
  • 1x for Leaping Flame (Tier 5 Loaded Spear)
  • 3x for Great Feather Mist Raven (Tier 5 Mist Raven)
  • 3x for Purple Fume Spark (Tier 5 Firecracker)
  • 3x for Suzaku's Lotus Umbrella (Tier 5 Loaded Umbrella)
  • 4x for Lazulite Sabimaru (Tier 6 Sabimaru)
  • 3x for Lazulite Axe (Tier 6 Loaded Axe)
  • 4x for Lazulite Sacred Flame (Tier 6 Flame Barrel)

Where to Find Fulminated Mercury

• Drops from Ministry Gunman in Ashina Outskirts.
• Drops from Ministry Gunman in Ashina Castle.
• Drops from the Gunmen patrolling the area at the Poison Pool Idol in Ashina Depths (Rare).
• Drops from the gunmen behind Gun Fort Idol. - note, may only start to drop after the Guardian Ape boss has been defeated (at least on 1st play through).
• 2x can be found at the Hirata Estate near the second Juzou encounter (2nd Memory)
• 1x can be found in Bodhisattva Valley behind a rock across an island with white monkeys,  in the poisonous water area.
• 1x can be found in Ashina Outskirts after it is set on fire, near the Ogre, next to a canon.
• 1x can be found in Ashina Outskirts after it is set on fire, at the top of the stairs where the original Ogre was.
• 1x can be found in Ashina Castle by the stairs to the castle tower after it is set on fire.
• 1x can be found in Ashina Reservoir after it is set on fire, behind Seven Spears miniboss.

Fulminated Mercury Notes & Tips

• Players can only carry a maximum of 99 material\
• Trivia --> The phrase "tweak of chemistry" in this item's description could be a reference to the Breaking Bad episode "Crazy Handful of Nothin'", in which the main character Walter White uses a modified form of fulminated mercury as an intimidation tactic to secure payment for the drugs Tuco stole from his partner. After destroying the thief's office with and receiving his money, the thief asks him what he used to create the explosion. He answered "fulminated mercury - a little tweak of chemistry". 
• User experience --> Can be farmed with Bell Demon buff before getting locked out of Ashina Outskirts from Cannoneers in Gun Fort. From my attempts at this I gathered 4x from 20 runs with first loot increase in Monk tree and balloon. Hadn't even got a single one before that, I was mainly just getting some powder.
• User experience --> Second the above post, but with both Monk tree increases, balloon, and Demon Bell averages 1+ per run. There are 2 gunmen at the bridge to take, 3 gunmen (1 tower 2 ground) and a cannoneer after passing through the gate (back toward Outskirts), and another 3 gunmen (all tower) and a cannoneer as you near the final shrine. 10 chances at this; it goes quickly and can all be done in a single balloon if you’re fast.
• User experience --> After Ashina is ablaze, use the Ashina Outskirts - Stairway Idol , the Demon Bell Buff activated and a Mibu Balloon active, kill the Ministry Rifleman on the Tower, the two on the Ground and then follow 2 patrolling Ministry Soldiers towards Ashina Castle. You will have several Rifleman to kill and if you are fast, you can kill all of them with 1 Balloon. I received 0-1 Mercury each Run on average.
• User experience --> (Tested in NG+) With Demon Bell active and Most Virtuous Deed, go to the Ashina Castle Idol once Ashina is ablaze and look to the stairs. There are 3-4 riflemen (signified by the gun on their back) and each has a chance of dropping a Fulminated Mercury. It takes as little as 20-30 seconds to kill them, rest, and repeat, and it took me at most 10-15 minutes to get 8 Fulminated Mercury. Note that I did not use Mibu Balloons, so this could go even faster.
• User experience --> Drops from the Cannon enemies in Ashina Depths, near the Poison Pool idol. Appears to be a rare drop, found this out by farming them. Starting from the Poison Pool idol, go up the wall and backstabbing the 1st Cannon enemy. Grappling across the trees to the right of him to the 2nd Cannon enemy and drop kill him. Finally grapple using the closest tree to the right, and you drop behind or close to the 3rd and final Cannon enemy. Grapple up and drop back to the idol, rest, and repeat. Earned 3 in about 3-4 mins
• User experience --> The Cannon enemies before the Gun Fort idol began dropping this after the Guardian Ape Boss was defeated. Multiple farming runs before that produced yellow gunpowder as a rare drop and no Mercury. After the Guardian Ape was defeated, the loot tables seemed to shift, either because of the boss itself, or obtaining the final last prosthetic tool from the Ape but the loot table shifted before the tool was installed. The new loot table seems to provide yellow gunpowder fairly often, & Fulminated Mercury rarely (at about the same rate as yellow gunpowder dropped before defeating the Ape).
• User experience --> Farmable from the ministry soldiers at the ashina castle idol once Ashina is ablaze.   Using Mibu possession balloon and golden vortex prosthetic tool, sneak up behind the group of ministry soldiers with golden vortex loaded and unleash the vortex.  You probably can do 2-3 runs from the idol on a single possession balloon, and should be able to get at least one fulminated mercury.  I was able to farm more than a dozen in <30 minutes using this method.