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IOTSPTS:
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Object Number:Class:
15
ConcordArea of Effect: Object Classification System
Common
RarityFrequency
Very useful
UsefulnessDuration
Majority
LocationIntensity
Description
Dipotassium octaoxoiron sulfide, commonly known as Firesalt, is a compound characterized by a significant thermal reactivity and a distinctive orange coloration. The object's structure, composition, and stability vary based on the formation method and the presence of mineral impurities, which also play a critical role in determining its overall behavior. Firesalt's various properties, paired with its multiple unique applications, make it one of the most important and useful known objects of the Backrooms as a whole.
Chemical Composition
The origin of Firesalt's properties finds roots deep inside the crystal's chemical composition. The molecular structure is composed of covalent bonds, with a chemical formula that can be represented as:
K2FeSO8
Each element in the formula brings a different characteristic to the crystal:
- K (potassium) is an alkaline metal that favors weak structures1;
- Fe (iron) gives the typical orange coloring to the crystal;
- S and O (sulfur and oxygen) contribute to the crystalline form: they make it slightly fragile, lucid, and reactive.
The interactions between Firesalt molecules form a crystalline lattice2 that remains relatively stable at room temperature but is vulnerable to changes in heat. Due to its anomalous properties, each molecule contains an impossibly high number of bonds, making the overall crystal unstable. If the lattice structure is disrupted3, the molecules react with their surroundings in an attempt to rebalance their bonds. This process triggers a significant release of heat as the bonds break.
In particular, the release of heat and explosive power are directly proportional to the purity and size of the crystal. The bigger and purer the crystal, the larger and more potent the explosion will be. Another relevant factor is the chemical composition of the air where the explosion happens: if it contains elements that are reactive to the ones found in the crystal composition, the explosion will be greater and faster4.
While being highly reactive, the lattice demonstrates a relative hardness to scraping, classifying in the Mohs scale of mineral hardness as a 75.
Formation
Firesalt can form naturally from two different processes depending on the environment, which give it a different crystal structure and slightly different properties.
Fusion Crystallization
A picture of a huge firesalt deposit provided by The Harmouth Speleological Society inside deep caves of Level 8.
Firesalt can form by fusion inside any cave-like level via a combination of different gases6 that rise from deep fractures or cavities with cold currents coming from the upper areas of the caves. Here, the hot vapors cool off and deposit on the surfaces of the caves as droplets of liquid, which start to crystallize. The process goes slowly7 at around 50°C, permitting the formation of crystals of many sizes, with the smallest being being 5-10 cm and the biggest 5-6 m.
Over the course of years, or even decades depending on the chemical composition, the crystals form in different shapes. The most common ones are the rosetta structures, similar to the famous Desert Rose. During this process, the crystals gain their notorious exothermic property: part of the heat used during their formation gets partially stored inside of them and will only be released if broken.
The resulting crystal can be represented via this stylized structure diagram:
O-O-O--O
/ / \ \
O---Fe O S
\ / \ /
O O
\ /
K KVisualize this structure being repeated one on top of the other inside huge stalactite-like formations inside the surfaces of caves.
This variant is the most stable, forming well-defined crystalline structures that resist degradation. Fusion-formed Firesalt can accumulate in cavernous deposits, much like sulfur or other volcanic minerals. These can be seen both in ceilings and walls, forming aggregates that resemble petrified fire tongues lunging towards the center of the caves.
Sublimation
The second formation mode is sublimation, a process occurring in environments with high thermal gradients, such as volcanic caves and geothermal fissures. In this scenario, vapors rich in Firesalt components deposit directly as solid crystals without passing through the liquid state.
This process occurs when the gaseous molecules undergo condensation upon encountering surfaces maintained at significantly lower temperatures than them. This leads to the formation of needle-like crystals, similar to feathers or icy fangs. These minerals are highly porous and prone to fragmentation even at the slightest touch, causing small explosions. The structure is weaker thanks to the presence of extra bonds to potassium atoms, which are highly unstable, as the element can only withstand a single bond8.
The resulting crystal can be represented via this stylized structure diagram9:
O
/ \
O-S-O
\ /
O
\
K---Fe---K
| / \ |
O--O---O-OImagine instead this structure being repeated one on top of the other inside thin stalactite-like formations on top of walls and ceilings of corridors and rooms
The Influence Of Impurities
An example of a Firesalt crystal with impurities that give distinct purple tones.
Akin to other types of crystals from the Frontrooms, Firesalt can rarely present streaks, stains and colored inclusions. These variations of its look are the product of the incorporation of impurities, which infiltrate inside the crystal during the growth process. Said variations can change depending on the formation process: while fusion impurities tend to form concentric bands that follow the growth lines of the crystal, sublimation impurities deposit into chaotic streaks and irregular stains.
In particular, the incorporation of the impurities can happen in two different ways: smaller particles of other minerals getting trapped inside the crystal lattice during the formation or molecules transported by vapors staining the surface10.
| Elements | Resulting color | Position inside the crystals |
|---|---|---|
| Fe(Iron) | Yellow, red, or brown | Streaks or rusty spots |
| Cu(Copper) | Green, turquoise | Spots or branching streaks |
| Mn (Manganese) | Pink, light purple | Linear streaks along growth layers |
| Ti (Titanium) | Milky white | No clear position, opacity augmented |
| Pb (Lead) | Grey, silver | Bright point inclusions |
| S (Sulfur) | Yellow | Long streaks |
| Cl (chlorine) | Transparent, white | Frost-like spots11 |
Pyroil
As previously stated, Firesalt liquifies at temperatures higher than 47°C. The result is a substance known as Pyroil. Colored in an intense and slightly translucent orange tint, Pyroil emits a mild orange light coming from the residual energy of the liquification. With an odor of burning sulfur mixed with a metallic scent, similar to the smell of hands after rubbing on copper coins, iron impurities can give it a smell similar to blood.
Similarly to a dense oil, the liquid can slide slowly on inclined surfaces and float on water. This last property, paired with its high reactivity, gives the possibility for the liquid to be lit on fire as the presence of sulfur reacts with water, releasing flammable gases like hydrogen sulfide.
Considering the characteristics stated above, some scientists believe that Pyroil could be the liminal echo equivalent of Greek Fire, the historical weapon used by the Byzantine Empire in medieval times. This theory is supported not only by their shared characteristics, but also by the fact that its earliest recordings, brought by The Lost, date back only to the 5th century CE.
Extraction Practices
Forming even inside rooms and corridors, the sublimated Firesalt is the easiest variant to collect. Generating in smaller clusters on concrete walls, the crystal can be collected without causing any dangerous release of heat.
Fusion Firesalt, while having more useful applications than sublimation Firesalt, is trickier to collect. This crystal only forms inside cave-like levels12, which usually contain large amounts of entities. In addition, this version can usually be found inside large clusters and can even fill up entire caves. This makes their extraction perilous, as breaking a large firesalt crystal may release large amounts of heat that could either deeply scar or directly kill its collector. Mining large clusters may also endanger the general stability of the levels they are mined from, similarly to what happened with a Leaders guided operation inside Level 8, where breaking a 5-meter crystal made the entire ceiling of the cave fall and detonated the other crystals of the cluster.
While direct extraction is the most relevant method used by large groups to obtain copious amounts of the crystal, small iterations of the object can also be found inside crates and containers inside environments like Level 1 and Level 3. This is the advised method of obtaining Firesalt for singular wanderers and small groups, considering the others are dangerous to perform without proper equipment.
Uses
Simple Tasks
Due to being easy to find in the majority of the levels, and its heat-releasing properties, Firesalt can come in handy in survival situations.
First and foremost, the simplest use of Firesalt is as a firestarter: thanks to its heat-releasing abilities, a small portion of the object can be cracked near a dry pile of wood, bark, or lichens to light it on fire. This makes the crystal a great replacement for lighters, while the presence of sulfur impurities could make the fire easier to light. This ability is also carried to its liquid version, as Pyroil can easily be lit on fire even in damp or low-oxygen environments.
The heat abilities of Firesalt can also be used to sterilize water from harmful substances and dangerous bacteria like Staphylococcus liminalis13, a process made easier thanks to manganese impurities, which make the crystal even more reactive in water.
If instead a crystal is dropped inside a container of water, the crystal will react releasing vapors. In case of anomalous liquid like Almond Water or Cashew Water, it will produce vapors that carry the waters' properties. Both Ariane Circle's Team Hippocrates and The Doctors have been known to use this ability to help distressed wanderers and cure the first stages of the Wretched Cycle thanks to the properties of gaseous Almond Water.
In the absence of either Pyroil or a material to light up, small Firesalt crystals can be used as a hand or body warmer inside cold environments. In such cases, the simplest uses, as explained inside Camp Amber's guide to survival, include putting the crystal inside small bags and then crushing it to release heat for a few minutes. This usage becomes even more relevant in the presence of lead impurities, which amplify the duration of the release. The Backrooms Robotics managed to expand this usage to create a survival body armor set with built-in sacks that can be filled with Firesalt. The sacks will activate automatically and crush the salt after temperatures reach a certain lower bound.
The same group has also specialized in using Pyroil as a fuel source. Burning easily after touching open air, the liquid is contained in cold and airtight containers, which are then connected to any type of machinery which uses heat as fuel. Being usually used as a replacement for Frontrooms burners like gasoline, the liquid is a solid but perilous alternative, as if stored incorrectly it can easily take out both equipment and people.
As a last note, firesalt cannot harm its user if only used in its fine powder form, bringing it to become a classic ingredient inside certain recipes. Since their earlier days in the Backrooms groups like the Lost used Firesalt to give a spicy flavour to their recipes. In particular, using a version with chlorine impurities, the spicy flavour becomes even greater. Some of the most common recipies can be found in the Ultimate Backrooms Cookbook.
Basic Weaponry
A demonstration of a firesalt sword by a member of the Eyes of Argos.
The Church of the Veiled, and to a lesser extent the Eyes of Argos, have been using pyroil since antiquity to create flaming swords. Their creation involved forging special swords with particular grooves covered with a hardened ceramic material resistant to heat, which could contain Pyroil. The liquid, viscous by nature, remained attached to the grooves, and after a flicker, it would make the sword light on fire. While giving a great advantage in combat, The fire disappears rather quickly, however, as all the pyroil would be consumed after 25-30 minutes, thus explaining why the practice remained limited to certain groups and has nowdays been dropped in favor of modern firearms.
Bows using Firesalt projectiles, however, have remained relevant through the years thanks to its versatility. Depending on the quantity and reactivity of the single crystals, the projectile could either have the effect of creating small controlled explosions, or simply light the surrounding area on fire thanks to the release of heat.
Explosives
If Pyroil is left cooling off, it will return to crystal form. If this is done manually inside casts, Firesalt ingots are created. While these ingots cannot be used to forge weapons due to the crystal's weak structure, they found their best use as explosives.
While normal crystals can be used too, ingots become way more useful thanks to the possibility of changing their chemical structure while they cool off. This forces what would be the natural deposition process of impurities to a chance to expand its explosive capabilities: mixing with Pyroil iron and copper can enhance the generated heat at impact.
This brings the ingot to work similarly to TNT, equating to approximately half the energy of a dynamite stick for a firesalt ingot of 100 g. This makes the object capable not only to defend bases from hordes of entities, but also as a tool of war. It must be noted that the manufacturing of ingots requires huge industrial capabilities, considering that only the smaller crystals can be collected without risk. In addition, an ingot capable of doing great damage may require dozens of small crystals, as a major part of their mass will be lost during their liquification and transformed into heat.
Tools of War
One of the few hand grenades remaining from the war.
Firesalt can be used as a component of projectiles for many kinds of weapons. The most notorious ones are Backrooms Robotics manufactured "Dragonspark" projectiles. Removing the risk of an explosion during the loading of the weapon thanks to titanium impurities, and stabilizing the crystal using a special polymer, these projectiles are composed of a special Firesalt tip that explodes on impact.
A similar usage is found inside simple hand grenades: a clay shell filled with sublimation Firesalt crystals would activate on impact by releasing heat and glowing vapors. There has been proof that this explosive was used the first time during the first years of the Leaders-Emstable War, where the Leaders employed the factories found inside Scene-09.9, while Emstable expanded their compounds inside Level 22 in an arms race to fabricate huge amounts of grenades.
In the case of Pyroil, it has been used across history as a defense mechanism during sieges. Melted inside big cauldrons and then lit on fire, the liquid would be thrown off to kill any enemy present either under walls or windows. The biggest example can be found in the siege of The Sanctum Subterraneus by the Church of the Veiled in 738 CE. The battle consisted of constant attacks at the walls of the fortress, which were held off by throwing a combination of Pyroil and Deathmoth powder, resulting in the failure of the siege.
Methods Of Mass Destruction
During multiple notorious terrorist attacks on the 29th of September 2021, by the hands of the Followers of Jerry that were simultaneously at Bases Alpha, Beta, Gamma, and Omega, the cult of the parrot detonated a series of explosives that released Firesalt into the air as dust and granules. The action triggered uncontrollable flames in the densely-populated areas and destroyed critical infrastructure, bringing the deaths of 407 wanderers and 128 operatives. This is only one example of how, if obtained in large quantities, the crystal can be used as a weapon of mass destruction.
Another method of destruction, albeit only threatened by the U.E.C. leader Thaddeus Cross, and never used, is mixing huge quantities of Firesalt and water: while in a smaller scale it can bear no harm, copious quantities of water and Firesalt can enact a violent chemical reaction. This could generate toxic water vapor and corrosive gases, causing instant death or serious long-term health damage and making nearby areas uninhabitable.
As a last note, during the Veiled Conflict, Firesalt emerged as a critical point of contention due to its proposed application in the development of a Firesalt-powered rocket launcher: a theoretical weapon capable of penetrating fortified structures and incinerating targets upon impact. The project, though never realized at full scale, represented a potential paradigm shift in weaponized materials research.
However, all known blueprints and prototypes were irretrievably lost during the terminal phase of an associated operation. Following the conclusion of the conflict, unverified reports began to circulate regarding remote, abandoned Veiled laboratories, that may still house fragments of the original designs.
Multiple joint research expeditions have been conducted in an effort to locate these facilities. To date, no conclusive evidence has been recovered, and the existence of surviving documentation remains, at best, speculative. Firesalt’s full potential, as well as the true scale of what was lost, may never be known.
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