Kryptonite

**Kryptonite** is a radioactive mineral from the planet Krypton. Following Krypton's destruction, some kryptonite found its way to the planet Earth. The day Krypton died, large quantities of kryptonite also rained down on Krypton's sister planet, Daxam.

There are several types of kryptonite, such as **Green Kryptonite**, **Blue Kryptonite**, **Red Kryptonite**, **Silver Kryptonite**, **Platinum Kryptonite**, **Synthetic Kryptonite**, **Black Kryptonite**, and **X-Kryptonite**. Exposure to kryptonite can have a wide variety of effects depending upon its color and present form, the majority of them detrimental if not outright deadly.

## Overview

### Effects on Kryptonians

"*Kryptonians are nearly indestructible on Earth. How could that blade hurt me?*"
"*Unclear. I've never seen anything like it. It's definitely not from this planet. It seems to be emitting a specific radioactivity that's damaging to your cellular structure.*"
—Astra and her associate discuss a kryptonite knife's capabilities[src]
Kryptonite is normally green, and Kryptonians exposed to the element will become weak within close proximity to it or if pierced by weapons laced with or made from the substance, and prolonged exposure is fatal. Kryptonite is comprised of sodium, lithium and boron, as well as elements not found on Earth.[1] Kryptonite's effects are radioactive in nature and therefore cannot penetrate the element lead. The radiation of the mineral can be harnessed and used independent of the substance itself to harm a Kryptonian; usually appearing in the form of artificial light emitted from certain machinery.[2] It has even been used as anesthesia or a sedative against Kryptonians due to its effects. Kryptonite inside the body causes green glowing veins to protrude from the skin of a Kryptonian and the physical pain it causes becomes unbearable at that point (as seen when Sam Lane injected Astra with liquid kryptonite to torture her for information).[3] Physical signs of being affected by kryptonite are somewhat fever-like; including nausea, weakness, dizziness, vertigo, fatigue, pain and loss (or near loss) of consciousness. Physical contact with kryptonite of higher intensity is enough to cause burning pain. Kara described the kryptonite poisoning as like having "nails in [her] blood".[4]

As seen with "Ultraman" (a Kryptonian from Earth-27A), being hit with green kryptonite only made him stronger (like what happened to Bizarro of the regular multiverse's Earth-38), though, unlike Bizarro, the kryptonite didn't degrade his body or mind.[5]

X-Kryptonite has a similar effect on the Inverse World's Kal-El as green kryptonite does on Kryptonians.[6] However, in the Inverse World, green kryptonite actually heals and strengthens Kryptonians rather than weakening them; even if those Kryptonians are native to a universe where kryptonite would usually have negative effects on them. Nonetheless, as seen with the Inverse World's Kal-El, using green kryptonite too frequently ultimately causes the user's physical appearance to become disfigured and induces headaches.[7] This also seemed to have altered his personality as (due the fact he'd believed them to be aligned with Ally Allston) he killed two members of the Supermen of America;[8] a line he usually wouldn't cross.

### Effects on humans

"*Did that just pulsate?"* *"This is why no one can help me."* *"This from the kryptonite? You said you were fine.""I thought I was.""I knew it could pierce the Batsuit, but, when you survived Tommy shooting you, I assumed it meant it was only fatal if the shot hit a vital organ.""No. Kryptonite kills; just hella slow.*"
—Luke Fox and Ryan Wilder discuss her kryptonite wound[src]
Although simply being around green kryptonite doesn't adversely affect humans the way it does Kryptonians, having it pierce the skin—such as being shot with a chunk of kryptonite in a manner similar to being hit with a regular bullet—can still cause terminal radiation poisoning. Even if the kryptonite is removed from the wound right after being shot with the stone, this ultimately leads to slow and painful death in humans.[1]

### Effects on meta-humans

As seen when "Bizarro" (a coma patient who was altered into a "reversed" duplicate of Supergirl by Maxwell Lord) was shot with bullets made of green kryptonite, in spite of her strength being equal to Supergirl's, her powers work in a manner directly opposite to a Kryptonian; being hit by green kryptonite unexpectedly corrupted her; physically and mentally degrading her, and only made her stronger[9] (though Bizarro is meta-human rather than Kryptonian). In the case of Kyle Cushing (who'd been empowered by X-kryptonite by Tal-Rho's experiments to turn the people of Smallville into his own army by using X-kryptonite to place the consciousnesses of deceased Kryptonians inside the bodies of humans; thus making those people like meta-humans to a certain degree),[10] being around green kryptonite impacted him in much the same way it would a Kryptonian (thus, shooting him with kryptonite while the Kryptonian persona in his body was active presumably would've affected him in the same manner as it would a regular Kryptonian).

As seen with the Inverse World's Lana (who'd somehow gained powers similar to those of an Inverse World Kryptonian), X-kryptonite weakened her in the same manner it had done to the Inverse World's Kal-El.[11] It's likely green kryptonite would influence her in the exact same way it would an Inverse World Kryptonian.

However, how being shot with green kryptonite would affect other meta-humans (such as the Flash), or if it would influence them any differently than it does a normal human, is unknown, while being around it doesn't seem to affect them any differently than regular humans.

## History

### Green Kryptonite

After the destruction of Krypton, samples of kryptonite fell to Earth, and also rained down upon Krypton's sister world, Daxam.[12]

A short time after J'onn J'onzz started posing as Hank Henshaw and assumed leadership of the D.E.O., the organization received reports of an asteroid that had just landed in the desert. Since Superman occasionally worked with the D.E.O. at that time, he accompanied J'onn to investigate. Upon arrival, in the darkness, J'onn saw something glowing emerald-green in the crater. While J'onn was unaffected by it, being near it severely weakened Superman. This led J'onn to name the substance "kryptonite". Because of the threat it posed, Superman wanted to destroy it, but J'onn kept it to use as a weapon against other hostile Kryptonians. This led to a falling out between the two that wouldn't be mended until several years later when J'onn entrusted all of the D.E.O.'s kryptonite to Superman to get rid of in order to keep it out of the wrong hands.[13]

At some point after declaring his war on Superman, Lex Luthor created a device designed to release kryptonite into a planet's atmosphere, thus making that entire planet uninhabitable to Kryptonians.[14]

Just as Kara was starting out as Supergirl, she was on her way to help deal with a fire, and was knocked out by kryptonite darts, she then awoke at the D.E.O., held down by cuffs of kryptonite, with Director "Hank Henshaw" (J'onn J'onzz in disguise) informing her of what the substance was. Alex Danvers (Kara's adoptive sister) then arrived in the room and removed the cuffs; telling "Hank" they weren't necessary.[15]

Alex taught Kara to fight in a room lined with low-intensity kryptonite emitters; just enough for Kara to be brought down to normal strength (roughly 18% of her typical physical capacity).[15] In the field, Alex utilized a sword made from kryptonite, which she ultimately used to kill Astra.[16]

Project Cadmus found a way to turn humans into cyborgs (known as "Metallos"), powered by hearts of green kryptonite.[17] The "Metallo Procedure" can also be used on the dying to enable them to make a full recovery, and while a Metallo will die if their "heart" is removed,[13] they can be rebuilt again; allowing that individual to be resurrected.[18]

When Mon-El's mother and father (Rhea and Lar Gand) arrived on Earth looking for their son, but Mon-El said that he wished to stay on Earth, his parents—especially his mother—refused to let him stay with his new family. When Kara decided to try to just talk to Rhea, the latter met with Kara and Mon-El at the Fortress of Solitude, and, as Kara learned by being near Rhea, the latter had a pair of kryptonite daggers with her, which she explained that she'd had made from kryptonite that fell upon Daxam when Krypton died[12] (with the fallout of that planet's destruction endangering Daxam; thus the reason Mon-El had been sent away from Daxam in the first place). She then attacked Kara with the daggers, prompting Mon-El to agree to go with Rhea to make his mother stop hurting Kara.

A short time later, Kara, J'onn and Winn ended up using a transmatter portal to get themselves onto Rhea and Lar Gand's ship to rescue Mon-El (who, in spite of reluctantly agreeing to what his mother wanted, was still being taken against his will). In the fight that ensued aboard the ship, Rhea's daggers ended up getting sucked out a broken window into the vacuum of space. After Lar Gand ultimately allowed Mon-El to stay on Earth, as he could see that that was what his son truly wanted, Rhea murdered her husband and vowed to make Earth suffer for taking her son from her.[12] During the Daxamites' subsequent invasion of Earth, on Lillian Luthor's urging, Winn and Lena modified a version of Lex's kryptonite bomb to disperse lead into the atmosphere as a stoppage measure to force the Daxamite army to leave Earth. Lena entrusted the machine's remote to Kara so that only the latter would be able to turn it on.

When Rhea refused to withdraw her forces even after being overpowered in a fight against Supergirl, Kara reluctantly activated the device; killing Rhea and forcing the army to retreat. Sadly for Kara, this also required Mon-El (who'd become her boyfriend) to leave the planet. After Mon-El left Earth, the pod he was flying ended up getting sucked into a temporal disruption,[19] sending him to the thirty-first century. In the thirty-first century, he received a cure for lead poisoning; making Earth's atmosphere safe for him again, and went on to found the Legion of Super-Heroes.[20]

The Nazis of Earth-X presumably came across Kryptonite at some point in their universe as they'd turned at least one of their soldiers into a Metallo, powered by a heart made of green kryptonite.[21]

After Kara was badly beaten in a fight against Reign,[22] the Legion of Super-Heroes used their future technology to heal her. The Legion knew from future history that Supergirl would survive, and that Reign would leave eventually; but they didn't know when they'd be rid of Reign, or how it would happen. A short time later, after Reign declared war on all criminals and law enforcement officers alike, J'onn decided to initiate the Sundown Protocol against Reign. This was a last-ditch option intended to take down Superman if he were to ever go rogue. This meant using all weapons that could be used against a Kryptonian; sound bombs, red sun grenades and more—kryptonite included.

Winn reminded J'onn that Clark had gotten rid of all the D.E.O.'s kryptonite, but J'onn said that they still had kryptonite the D.E.O had recently confiscated from Thomas Coville;[23] the founder and leader of a cult dedicated to worshipping Supergirl (the last thing he tried doing before being apprehended had been to attempt to detonate a bomb under a packed stadium, so that Supergirl would save everyone inside; with Thomas hoping they'd be "converted" to his cause). When Supergirl tried approaching it, she'd weakened, due to the fact that the bomb had soil from Krypton on it; which contained traces of kryptonite. Kara then took advantage of her weakened state in the substance's presence to cut herself in an attempt to prove to Coville that she wasn't a god.

This prompted Thomas to try to stop the bomb, but he couldn't. Alex then arrived on the scene and removed the kryptonite (which the D.E.O. then kept), and Supergirl was able to use her heat vision to send the bomb far enough underground so that no one was hurt in the explosion; though it did awaken Mon-El (who'd travelled 12,000 years into the past with the Legion of Super-Heroes as part of a mission, and the group had subsequently put themselves to sleep, intending to reawaken in the thirty-first century) from stasis in a ship buried in the Earth).[24] When everything was ready, the D.E.O. staged a bank robbery to draw Reign out. In spite of all their preparations, and utilizing all of their anti-Kryptonian weapons against her at once, she managed to shrug everything off—even the kryptonite—and escape; also breaking Alex's leg in the scuffle.[23]

A little over a year after Rhea's attack, a version of Lex's device was used by the Children of Liberty to pump kryptonite into Earth's atmosphere,[25] though, on Alex's urging, Lena was able to put Kara in a special suit designed to protect the latter against kryptonite, which Kara then wore until they could make the planet's environment safe for her again.[26] After special nanites built by Brainy and Lena devoured the kryptonite in the air, Kara was able to remove the suit.[27] though she later donned it to travel into outer space,[28] and again to protect herself from kryptonite weapons utilized by Lex Luthor.[29]

At some point after Superman arrived on Earth in Earth-99's universe, that Earth's Bruce Wayne started keeping a stash of kryptonite in his lair, and wound up murdering the Kryptonian. After Bruce was accidentally killed by Earth-1's Kate Kane (who'd been protecting Earth-38's Supergirl from Bruce), Kate stole some of Bruce's kryptonite. Lex attempted to use a piece of kryptonite against Clark Kent of Earth-167, but because Clark had given up his powers, it had no effect on him and Clark snatched it out of Lex's hand and threw it into a field.[30] When Kate told Kara about it a short time later, the latter told Kate to keep it; trusting her to not use it.[31]

In Earth-Prime's history, Kara experienced the effects of green kryptonite for the first time the night of her senior prom; when a meteor shower fell upon Midvale on May 26, 2009. After meteors began falling near the school, she wound up punching one of these asteroids as it fell; attempting to keep the comet from hurting anyone. Due to the fact that the meteor contained kryptonite, Kara ended up getting cut by the stone.[32] After Lex Luthor sent Kara to the Phantom Zone in 2020,[33] Brainy and Nia wound up time traveling back to this event in order to get a chunk of the meteor with Kara's blood on it; as they needed a sample of her DNA to locate her within the Zone. After they successfully obtained what they needed, they returned to the present.[34]

Lucius Fox stated in his journal that green kryptonite is the only thing capable of penetrating the Batsuit.[35] Alice later read the journal and learned that the substance can cut through anything. At some point, Professor M. Darby analyzed a sample of kryptonite, although he did not know its true name; just that it was a "rare meteor rock," learning of its cutting power.[36]

The Earth-Prime version of the D.E.O. kept large deposits of green kryptonite until it was stolen by Rama Khan,[37] to be used to kill Kara; requiring her to have an Anti-Kryptonite suit created by Lena Luthor, though Kara wound up engaging in combat with Leviathan before the suit was ready, and Lena had to deliver it to Kara in the field via drone.[38] When Lex nearly killed Kara with kryptonite radiation from a ring-like weapon he had on hand after meeting with her at the Fortress of Solitude and Lex subsequently left Kara for dead, the Anti-Kryptonite suit came to Kara via remote control once more, encasing Kara and she managed to recover from Lex's attack; subsequently rendezvousing with her team to battle Lex again a short time later.[39]

After Tommy Elliot (posing as Bruce Wayne) took Kate's shard of kryptonite from Luke Fox, he loaded the kryptonite fragment into a gun, proceeding to shoot Ryan Wilder (who had stolen the Batsuit after finding it in the wreckage of the plane crash that supposedly killed Kate, with Tommy now wanting the suit so he could pose as Batman). True to Lucius Fox's journal, the kryptonite went straight through the suit's armor and pierced Ryan's skin, leaving her injured and knocking her to the ground.[40]

"*Kryptonite is comprised of sodium, lithium, boron, and elements not found on Earth. As a result, this makes it the singular material that can penetrate the Batsuit, and the only fail-safe that protects the suit against corruption.*"
—Ryan Wilder reads up on kryptonite[src]
While Ryan did survive (fighting off Tommy and subsequently returning the kryptonite and the Batsuit to Luke) she, after examining her shallow wound a short time later, found that the kryptonite—even though the rock had been removed from her cut—seemed to be affecting her in a strange way; causing green veins to spread outwards from the site of the ballistic trauma,[40] with the wound only getting worse over time.[41] Eventually, it got so bad that in addition to the intense pain that the injury continued causing her, she also began experiencing episodes of severe vertigo and photopsia; prompting her to do more research on the stone's properties.[1] Later, the kryptonite made its way into Ryan's brain; causing her to begin experiencing hallucinations as well.[42] Ryan and her friends ultimately concluded that her only hope of surviving the kryptonite poisoning was the Coryana Desert Rose's universal healing properties.[42] Ryan nearly died of the infection, but the Bat Team managed to administer the Rose's serum to her in the nick of time; saving Ryan's life and allowing her to make a full recovery.[43][44]

After Kate Kane (who'd been brainwashed into believing she was Circe Sionis) convinced the Bat Team to give her back the Batsuit (claiming she wanted to get back to protecting Gotham), she knocked them out and trapped them in the Batcave. A short time later, she took the suit and cut it up; using a piece of green kryptonite to carve a diagonal line through the suit's emblem.[45]

John Henry Irons from another universe came to Earth-TUD25 after his home world was destroyed (presumably in the Anti-Monitor Crisis). Despite losing the last of his stock of kryptonite fighting Earth-TUD25's Superman, John decided he had to look for more, as it was necessary for his mission.[46] After looking in Moldova and Mongolia, he abandoned his search. When asked by Superman, Sam Lane revealed that he stockpiled a supply of kryptonite; enough for the world to be in short supply, stating that his reason for doing so was to avoid anyone getting their hands on the substance to use against Superman.[47] An officer under Sam Lane's command used kryptonite bullets against Superman when the latter was trying to shield Tag Harris from Lane's forces, making Superman very angry.[48]

At some point, Sam Lane developed Project 7734; an arsenal of kryptonite weapons made to kill Superman if he lost control and turned against humanity. When John Irons was apprehended for interrogation by Superman, Reno Rosetti took Irons and, after killing Lieutenant Jason Trask with Kryptonian abilities, went with his prisoner to Project 7734. Upon learning of this, Lane warned Superman that he may not make it out alive and to let his men stop Rosetti instead. However, Superman ignored his request and confronted Rosetti, who was armed with Project 7734's many weapons. Irons was told to leave by Superman before the hero began battling Rosetti. Superman was nearly defeated by Rosetti until he was killed by Irons, who was going to kill Superman with a kryptonite staff but was stopped by Lois.[49]

After Lois and Sam Lane began suspecting that something was up with Kyle Cushing, and Lois repeatedly failed to get in contact with Kyle's wife, Lana, Lois went to see them. When she arrived, she said she'd wanted to check in, but then got attacked by Kyle using his Kryptonian powers (bestowed by Morgan Edge's experiments) with the latter stating that he knew she'd come to check on him specifically. Kyle then grabbed both Lois and Lana by their throats, calling them weak. Lois responded by punching him; hitting him with a chunk of green kryptonite (presumably borrowed from her dad); stating that not all of them were weak. Her father, Sam Lane, then arrived with his troops and took Kyle into custody; negating Kyle's powers with power-dampening cuffs.

A short time later, after Kyle refused to cooperate and answer General Lane's questions in custody about a certain man's whereabouts, Sam had Kyle exposed to kryptonite lights, which he increased the intensity of when Kyle still wouldn't tell him what he wanted to know. Kyle later returned to his normal self when Superman released all the solar energy in his own body at once to create a solar flare in order to give the same machine that had empowered all of Morgan Edge's test subjects enough energy to turn everyone who'd been part of Edge's experiments back to normal (except for Leslie Larr, who was out of range at the time that they reversed the effects on all the other citizens of Smallville that Edge had recruited).[10]

After being overpowered by the combined efforts of John Henry Irons and Superman, Morgan Edge was taken into the custody of the D.O.D., with kryptonite lights shining on him in his cell.[50] A short time later, however, he broke out of the facility where he was being held and flew directly to Earth's sun.[51] Upon reaching the sun, Tal absorbed the energy of the Eradicator (which he'd been using to grant people Kryptonian powers, and he'd seemingly destroyed with his heat vision prior to be apprehended by John and Superman previously). This allowed him to essentially *become* the Eradicator; enabling him to use the Eradicator's capabilities on humans to create more Kryptonian Subjekts. He subsequently broke Leslie Larr out of D.O.D. custody (where, like with him, the D.O.D. had had kryptonite lights shining on her, though becoming the Eradicator seemed to have made him immune to the effects of kryptonite). Leslie then accompanied Edge to Metropolis, where they started attacking the city, with Edge empowering several of the city's residents with Kryptonian abilities; thanks to his new powers granted by the Eradicator. A short time later, when Edge attacked the van Sam Lane was driving; hauling Sarah Cushing along with Jordan and Jonathan. After the vehicle rolled over due to a collision with Edge, Sam asked the boys to reach into the glove compartment for a pistol loaded with kryptonite. Jonathan grabbed it and, on Sam's instruction, fired at Edge. However, Edge flew out of the way, grabbed Jordan, and flew off. Edge then took him to another location and used his Eradicator power to place his father (Zeta-Rho)'s consciousness inside Jordan.[52]

Mitch Anderson shot Superman with kryptonite to trap him and arrest him.[53] Mitch, at Tal-Rho's fortress then tried to shoot Superman with kryptonite again, but Tal-Rho jumped in front of Superman, taking the bullets instead. Superman later used his heat vision to destroy the pieces of kryptonite in his half-brother's body.[54]

### Blue Kryptonite

"*The compound is ready. The exact molecular opposite to green kryptonite.*"
—J'onn J'onzz[src]
The blue, molecular opposite of green kryptonite was created by Alex Danvers at the D.E.O. by reversing the ionic charge of green kryptonite. While blue kryptonite has no effect on Kryptonians, it severely weakened Bizarro and sedated her, allowing her to be apprehended. It also seemed to have a calming effect on Bizarro, removing her rage toward Supergirl and allowing her to think rationally.[9]

### Red Kryptonite

Maxwell Lord created a synthetic red form of kryptonite (though whether this kryptonite was made from scratch (like synthetic kryptonite created by Lena Luthor) or by modifying green kryptonite (similar to how Alex "made" blue kryptonite) is unknown) in hopes of subduing Non's next attack. However, it didn't work as intended; rather than weaken Kryptonians physically, red kryptonite alters their minds by weakening and gradually destroying their inhibitions, as well as bringing every negative thought to the surface. They can even feel its effects long after they have left its presence. As this happens, red, glowing veins momentarily protrude from the skin when they first come near red kryptonite and subsequently in times when the victim's actions and thoughts are most affected by the substance. Symptoms of red kryptonite infection first start as the Kryptonian becoming more abrasive and immature in personality and actions as their mental and emotional restraint is lessened. Eventually, the Kryptonian will be left without morality, patience, rationality or any cares, whatsoever. They can even develop narcissistic tendencies and arrogance that results in an inferiority complex. After having expressed their negative personality traits fully, the Kryptonian will become malevolent and prone to hostility and aggression, leaving them a danger to everyone around them.[55] However, Maxwell also developed a cure for it in the form of a red energy blaster that neutralized the red kryptonite in a targeted victim; as seen with Kara Danvers, this briefly knocks the affected Kryptonian out, as the substance then left Kara's body in the form of a red gas. This ultimately returned Kara to her normal self.[55]

### Silver Kryptonite

A silver colored form of Kryptonite that was found and used by Queen Rhea from the vast quantities of Kryptonite that rained down on planet Daxam. This kryptonite will cause a Kryptonian to fall in a deep and frightful hallucination where nothing from the outside world will stir them out of it until it leaves their system. When Superman confronted Rhea, she poisoned him with it and he was convinced that Supergirl was actually his greatest enemy, Zod, who had come back to destroy everything he loved. While under the effects of Silver Kryptonite, Superman was unable to hear Kara but only hear Zod talking. Unlike green kryptonite, silver kryptonite will not weaken or negate a Kryptonian's powers at all. When in large quantities, it will reveal itself as glowing silver veins on the Kryptonian's skin.[19]

### Synthetic Kryptonite

"*Is that a Kryptonite arrow? Why do you have a Kryptonite arrow?*"
"*In case an evil you ever showed up!*"
—Supergirl and Green Arrow[src]
At some point after meeting Earth-38's Supergirl in late 2016, Oliver Queen of Earth-1 commissioned arrows with heads made of synthesized green kryptonite in case he ever met an evil version of his Kryptonian friend.[5] He then used these arrows in battle against Kara's Nazi doppelgänger from Earth-X in November 2017.[21]

After J'onn J'onzz gave all of the D.E.O.'s remaining green kryptonite to Superman to destroy it, preventing Project Cadmus from further using green kryptonite against him and Kara, Cadmus was forced to create their own artificial version of green kryptonite. While their synthetic kryptonite does have the same effects on Kryptonians as natural green kryptonite, as well as being able to successfully power Metallos, it was proven to be too unstable, as seen with one version of Metallo (John Corben), it eventually exploded; killing the cyborg in the process while also releasing a large cloud of kryptonite gas, although Kara was able to avoid contact with it.[14]

In 2018, Oliver tried using an arrow made of his artificial green kryptonite (which seems to be more stable than Project Cadmus's synthetic kryptonite) against Ultraman. However, to the surprise of Oliver and the rest of his friends who'd united to face Ultraman, the latter wasn't weakened by the kryptonite at all; it only made him stronger.[5]

About a year after meeting Kara's Nazi counterpart, Barry Allen (who, as a result of an alteration of Earth-1's reality, had gained Oliver's skills as an archer and martial artist) and Oliver used kryptonite arrows (presumably made from Oliver's supply of synthesized kryptonite) to battle A.M.A.Z.O. and John Deegan, respectively.[56][57]

"*That wasn't Lex's kryptonite. I figured out how to make it.*"
—Lena Luthor[src]
Lena Luthor was able to create an extremely stable synthetic version of green kryptonite (which wouldn't explode;[58] a feat that even Cadmus could not achieve) which, after learning of Samantha Arias's Worldkiller persona,[59] she began using to contain Sam at L-Corp and (consensually) ran tests on the latter in an effort to find a way to get rid of Reign (though, when questioned by the D.E.O. on the matter, she claimed it was a stash of kryptonite Lex had kept in a vault in the lab, but later confided in James Olsen that she'd figured out how to make the kryptonite; it hadn't been Lex's).[60] After obtaining a sample of Harun-El, she was able to figure out how to make more of that type of kryptonite as well.[61]

At some point in Earth-TUD25's timeline, Sam Lane developed Project 7734; an arsenal of weapons made to kill Superman (though Sam hoped the military would never need to use those weapons). Among its inventory is a smoke-bomb-like weapon that releases synthetic kryptonite gas, designed to weaken a Kryptonian enough to be harmed by more traditional means.[49]

As Clark found out a short time after getting attacked by Reno Rosetti with the gas, it seems to affect Kryptonians in a strange way, as when Clark went to stop a robbery as Superman, the thieves' ordinary bullets left him with bruises. It also seemed to affect his Kryptonian-human hybrid son, Jordan, who became infected by being around his father afterwards; exhibiting symptoms similar to a cold, though much more severe. It quickly became bad enough that Jordan began having trouble breathing; as an A.I. of Jor-El at the Fortress of Solitude told Clark, the kryptonite was causing Jordan's lungs to fill with fluid, but due to his system cooling the air he breathed (his freezing breath), the kryptonite was essentially gradually freezing his lungs. As Jor-El's A.I. explained, the only way to get the kryptonite out of Jordan's system would be to do as had been done with Clark in the past (burning it). As Sam told his daughter Lois, the gas was untested, and they had no idea how it would affect Superman.[62]

After Leslie Larr was captured by John Henry Irons and Superman and subsequently taken into D.O.D. custody, with the threat that she and Morgan Edge posed seemingly eliminated, Sam Lane informed Superman and John that the next thing he planned to do was to get rid of the majority of Project 7734's weapons. He stated that he was wrong to think that Superman could ever go rogue, and intended to only keep enough kryptonite to contain Morgan and Leslie; the rest of Project 7734's arsenal would be enclosed in concrete and sunk to the bottom of the ocean. However, a short time later, Superman told Sam that, if anything like what Edge had done were to happen again, the D.O.D. would need the kryptonite Sam was planning to dispose of.

When Lois spoke with Clark about it, he stated that the people of Earth had the right to defend themselves against him if he were to ever be manipulated or corrupted; similar to what Edge had done to him (using the Eradicator to place Zod's consciousness inside Superman's body; and even though John Irons had managed to turn him back, Clark was concerned what he may have done next if he'd ended up killing John). Lois insisted that if weapons that could harm Superman existed, the wrong people inevitably would get ahold of them. After Clark explained his reasons for wanting Project 7734 to stay in place, Lois agreed, but refused to trust the D.O.D. regarding the matter. Clark then spoke to John Irons; saying that if necessary, John alone should have the capability to kill him. John honestly stated that he trusted Superman now, but Clark said that John had come to Earth-TUD25 striving to protect the world from Superman, and that's what he was asking John to do by leaving the latter in charge of Project 7734.[51]

### Black Kryptonite/Harun-El

*Main article: Harun-El*
Harun-El, or the Rock of Yuda Kal (also called black kryptonite),[63] is a very specific type of Kryptonite that is capable of making Worldkillers. It can also be used to destroy a Worldkiller.

On their home world or in Argo City, black kryptonite is harmless to Kryptonians. However, on Earth, touching the substance not only causes great pain to a Kryptonian, but also makes their powers unstable. It can also be used to split a Kryptonian into two separate entities (such as when Lena used it to separate Reign from Sam; one of them evil, the other good). When Kara used it to send herself, Reign and Sam into the Dark Valley to defeat Reign; preventing anyone else from getting hurt in the conflict, it split Kara in two beings—unbeknownst to Kara at the time—sending her duplicate to Kaznia.

Harun-El is also an incredible power source. It was able to power the dome of Argo City as well as sustain an ecosystem and the artificial gravity on the asteroid that houses Argo. Argonians were given a recipe to make the substance from elements on Argo, courtesy of Lena Luthor who figured out how to make it. When harnessed correctly, black kryptonite has mutagenic and healing properties on humans. Tumor masses that Lena was testing the serum on had unintentionally been made invulnerable. It was revealed that the powers bestowed upon human subjects proved fatal in the long run, with Lena's experiments focusing on removing the deadlier effects before proper use. After supposedly being perfected, the serum was used on James Olsen and Lex Luthor to heal them both.[63] Said version used on James was thought to be separated from the mutagenic part, but this wasn't successful and he gained temporary Kryptonian abilities; including enhanced strength, senses, durability, accelerated healing, flight and heat vision, until the drug was extracted from his body. Lex Luthor and Ben Lockwood at least gained the power of super strength, while the former also gained levitation with the Harun-El in his system, though somehow Luthor's version of the injection seemed more stable than either Ben or James's for unknown reasons, as he didn't suffer any noticeable side-effects from the serum. All three later had the drug forcibly taken out of their bodies.[29] As seen with Lockwood, while he did gain powers from the serum,[64] due to the fact that he injected himself was an unfinished version of the drug, his body began to gradually deteriorate,[65] though this stopped once the Harun-El was removed from his bloodstream.[29]

### X-Kryptonite

"*When I landed here, there were meteor showers all over the world for an entire week."* *"Right, remnants of Krypton. That's why there's kryptonite."* *"Right, every form of kryptonite, and the kind that landed here is buried in the mines.""Was X-kryptonite. So the only place in the world that has X-kryptonite is the only place that has people who've been exposed to it long enough to accept its effects.""Like Tag Harris. It's not Smallville Edge needs to build his army. It's the people.*"
—Clark Kent and Lois Lane begin piecing together what Morgan Edge is planning.[src]
X-kryptonite (sometimes referred to simply as X-K)[10] is a variant of kryptonite only found in Smallville on Earth. It is yellow in color and can endow humans with some Kryptonian-like powers, although the effects from accidental exposure can be unstable and debilitating.[66]

One night, Jonathan and Jordan Kent went to a bonfire with some of their classmates, and a fight broke out when Sean Smith pushed Jordan Kent after the latter kissed Sean's then-girlfriend, Sarah Cushing. In the commotion, Jordan wound up releasing a blast of heat vision, causing an explosion, which broke Tag Harris's arm.[67] Jordan's heat vision caused the explosion, but another material, some "yellow phosphorescence" (X-Kryptonite), was also present and affected Tag Harris, giving him vibrating powers.[68]

Large deposits of X-kryptonite were found in the Shuster Mine by Morgan Edge (who was actually a Kryptonian; with his real name being Tal-Rho) who intended to use it for his own ends, planning to create some kind of army.[68] X-kryptonite is used in machines that can bestow or increase powers. Morgan Edge used X-kryptonite on Derek Powell and empowered him, but Derek couldn't control the powers and ended up killing himself after a confrontation with Superman.[66]

A few days later, John Henry Irons showed Lois Lane the X-Kryptonite in the mine and gave her a sample, telling her that she needed to write a story about it.[48]

A short time after John Irons brought the X-kryptonite in the mines to Lois's attention (immediately after Lois and Jonathan were attacked by Morgan Edge's super-powered minions), Clark and Lois began realizing that Morgan Edge had conducted his experiments with X-Kryptonite on a wide variety of people, but the only ones who didn't suffer adverse effects were people who'd been living in Smallville for years, and thus, had continuously been exposed to the X-Kryptonite buried there. When Clark had crashed on Earth, kryptonite impacted all around the world for a week; all types of kryptonite made it to Earth in constant meteor showers that occurred during this time, but only Smallville had X-Kryptonite; thus the reason only people who'd lived in Smallville for years were gaining stable powers from it (by contrast to people like Derek Powell, who weren't from Smallville), and the reason Morgan Edge had specifically come to Smallville to find recruits for his army.[62]

After bringing Edge's associate Dabney Donovan in for questioning, Superman and the D.O.D. realized that Morgan Edge wasn't just giving people powers; he was actually placing consciousnesses of deceased Kryptonians inside their bodies using a device called an Eradicator (intending to resurrect Krypton of Earth). However, Dabney truthfully stated that he had no idea how the technology even works, and that in order to put a stop to Edge's scheme, they needed to place the consciousness of the one who invented it (Superman's biological mother; Lara Lor-Van) inside a host to speak to her (and, due to the nature of the procedure, that individual had to be from Smallville in order for it to work). Lana Lang immediately volunteered, and even though Lois was hesitant to allow her to do it, she eventually agreed to let Lana go through with it. Lara, through Lana, then stated that she'd never intended for her technology to be used for what Edge was utilizing it to do, and helped them to use the Eradicator to reverse the process. Due to Superman's weakened state following him releasing all the solar energy in his body at once (creating a solar flare) in order to give the Eradicator enough power to de-power everyone Edge had placed Kryptonian consciousnesses inside of all at the same time, this left Clark powerless until his cells had replenished their supply of solar energy, and he crash-landed at the Fortress of Solitude.[10]

There, Superman was met by Morgan Edge, who blackmailed Clark into joining his mission.[69] As the Eradicator, Edge then returned to the Shuster Mines and began the process of using X-kryptonite to eradicate the population of Smallville, but he was later defeated by Superman and John Irons.[70]

The government later contracted AmerTek to remove the remaining X-kryptonite from the Shuter Mines,[71] but before they began work, Phillip Karnowsky stole a significant quantity of X-kryptonite from the mines and converted it into an inhalable gas that granted the user temporary superpowers.[72] Candice Pergande sold the drug to Smallville teenagers, including Timmy Ryan, a member of the Smallville Crows.[73] The additional strength from the drug allowed him to become the Crow's starting quarterback and in response Jonathan Kent also began using the drug, gaining enhanced vision and reactions.[8] The sheriff's department became aware of the drug when Timmy's mother caught him taking it[53] and they swept through Smallville High School looking for it. At that point, Jonathan took Candice's stash to protect her, intending to dispose of the drug. He was caught and expelled. In order to fight and capture Superman's Inverse World counterpart, Mitch Anderson took various weapons from Project 7734, including several vials of X-kryptonite. After killing Superman's counterpart, Anderson went AWOL and stole the weapons and vials of X-kryptonite instead of returning them.[54]

John Irons' exosuit is powered by X-kryptonite.[11] His daughter Natalie later built a suit of her own designed to run on the same substance.[74] However, while she'd constructed her suit from the same material that was used in her father's armor, Natalie also coated her suit in a special lacquer made from X-kryptonite which rendered the suit indestructible, and thereby superior to John's suit.[75] However, she later applied the X-kryptonite lacquer to her dad's suit as well.