Hearth Stones

Making a hearth stone is easy. Any perfectly round rock will do. You set that rock on the table in front of you, right? You get in reeeeal close, and you stare at that rock like it's the center of the universe. Then just focus your eyes on a point behind the table, and bam! There's TWO rocks in front of you. But you can kind of see through one, and you know it's not real. Stare at those two rocks until you're sure they ARE real. Then you close your eyes, reach out with both hands, pick up a rock in each, and put them into the box. Then, and this is the most important part, DON'T LOOK. If you observe both balls together, it ruins the whole magic trick and the universe compensates. Sometimes violently...

— Rennard Vostok, Quantum Shaper (probably false)

A hearth stone is a fairly common device in the Five Nations, used for heating applications from cooking to steam power generation and smelting of metals.
Hearth stones have been a part of Adinite life since the first came down from the Temple of An in Heaven. The Gods forbade the use of fire, and only about five percent of the populace had any sort of ability to heat or cool materials through touch. They taught the first quantum shapers the secret art of the hearth stone, so that every Adinite would have access to clean water, cooked food, and comfort in their shelters.
The Sherdasan colonies were not given this knowledge. Rather than try to give the freshly awakened species a crash course in quantum mechanics, the Gods simply asked the Adinites to provide them offerings of more hearth stones. The faithful Adinites made hundreds of the devices and sacrificed them to the Gods, who in turn handed them out to the Sherdasans with a quick tutorial on which end was up.

Physical Appearance

Sizes vary by need, but the most popular for cooking or personal survival in the wilderness is a granite or marble U-shape about six inches wide and tall, and about an inch thick.
The base of the U will have a flat bottom to rest on, leaving the tapered points aiming upward. One arm of the U is sealed shut, while the other arm has a groove cut into one side, marked along the path with temperatures. In the groove will be some small adjustment lever, connected to a caged stone marble encased inside the arm. The interior of the arms is lined with lead, including a divider at the middle of the base where the groove ends.
Tips were traditionally made of copper, but more contemporary hearth stones can be tipped with silver, brass, or any desired metal as long as the melting point is higher than the maximum output on the stones. For the basic personal model, this is limited to around 400C.

Harnessing the Power of Improbability

The marble is the functional part of the device. Hearth stone marbles can be made of practically any mineral that presents in a crystalline form. Through quantum shaping, the eccentric and rare artists that make these are able to realign the crystalline matrix in a fractalized configuration. They then split the marble into two instances of itself, quantum entangled with one instance sealed in stone, unable to be observed.
When the marble is at the bottom of the track, at rest, the device does nothing. The two instances are at their closest point here, separated by a quarter inch of lead and unable to resolve into one. As the lever is moved up the track, pulling the visible marble further up the side of the U, the other marble mirrors the motion, moving up its own arm towards the tip.
As the two instances move apart, a differential is caused by the paradox, generating heat energy in a U-shaped arc between the tips that increases the further the marbles are apart. The device itself does not get hot, except the very points of the metal tips will be searing hot to the touch even after the hearth stone is turned off, until it cools naturally. During operation, this heat will remain focused on the point, but as it cools it will distribute throughout the entire metal tip and is soon safe to return to storage.

Caring for your Anomaly

There is very little that can go wrong with a hearth stone, as long as it is used properly. Hearth stones do not degrade over time, and can last several lifetimes.
Items should not be placed directly on the tips for heating, as this will cause heat to radiate back into the device through contact. The stone casing is resilient, but temperatures above 327.5C will begin to degrade the lead lining. If there is a breach in the lead coverage, especially the divider at the base, this may result in a feedback loop. Every attempt should be made to return the marble to base position, as even without the lead divider the two instances will still be close together and emitting less energy. This should prevent immediate danger, but consider the hearth stone unsafe for future use until the lead layer is fully repaired by a qualified metal shaper. It is also recommended to have the device inspected by a quantum shaper, if available.
Failure to deactivate the device when overheated or physically damaged may result in a quantum resolution. In most cases, and with no sense of rhyme or reason, the two primary outcomes are:
1) Both instances of the marble attract as though strongly magnetic, touch, and disappear with an indescribable backwards pop.
2) You are left with two perfectly identical marbles that do nothing.
In several reported or suspected cases, a third possibility exists. No first-hand witnesses or their remains have been found, but hearth stones are suspected to be at fault for more than a dozen catastrophic events throughout history, including the Five Years Fire in eastern Satium and the Brown Patch of Gibila.