Jtdylktuy

I'm working on an RPG in a world with some magical elements, like a type of energy (so far unnamed) inherent in animals and humans. Those with high amounts of this life energy in them are thought of as "pure", while those with low amounts are thought of as "corrupt". It has many properties similar to thermal energy (such as methods of transfer and shiny metals being able to reflect it). I took a lot of inspiration from physics lessons on thermodynamics.

There's also a mineral/ore in this world that is valuable because it is able to emit the previously explained life energy via radiation (whether at all times or only in certain conditions, I haven't decided yet, but it is able to do so at room temperature). Societies mine it and use it for protection because its pure energy repels the corrupt.

What already existing mineral could serve this purpose? If none, what elemental composition would allow this fantasy mineral to radiate thermal-like energy?

EDIT: I should've been more clear. I want some kind of mineral, whether real or made-up, that would reasonably be able to radiate the magical "life energy" that shares some properties with heat. If I end up adapting an already existing mineral to fit my RPG's lore or creating a new kind of mineral, either way works, but if I create a new one I'd like to have an idea of what compounds or elements would be necessary to make it serve "this purpose", i.e. be used by the people of my world for protection with what they would call its "aura of purity". I hope that clears things up.

There is no single hand-sized naturally occurring material that can continuously emit heat over long periods of time. If there was such a material, we would already be using it for power generation, wouldn't we? There are some possibilities, but none are ideal. However, you may be able to twist some of them into your story.

You have four options:

1. Radioactive materials. The three most abundant radioactive elements in Earth's crust are potassium, uranium, and thorium. All three are enriched in certain types of granites. In particular, thorium and uranium are abundant in the minerals monazite and xenotime. These minerals tend to concentrate in mineral sands, so they can be mined, concentrated in put into containers that can contain the heat, and then exploited. This is not something that I would recommend, because (1) it's radioactive, and (2) there isn't that much heat coming out of it.


2. Oxidation. Take for example, pyrite - fool's good. It is iron sulfide, unstable in the atmosphere. By crushing it to finely divided powder you are accelerating the reaction rate with the atmosphere, essentially allowing it to burn. The product is heat, sulfuric acid, and iron rust.


3. 
   Infra-red fluorescence. A material that absorbs energy in the form of visible light, and emits it back again in the IR region, which is then perceived as heat.


4. My favourite: An extra-solar meteorite containing material from a recent supernova. This material will be full of radioactive isotopes: Al-26, various actinides (plutonium, etc etc). It will be hot. The downside, is that it probably doesn't fit your story of "life energy" because handling it will probably cause radiation death very soon.

EDIT

Ok so here's an idea, which would be an elaboration of point 1. A naturally occurring nuclear reactor forms a concentration of fission products. This essentially heat-producing nuclear waste, and it can be mined (as requested in your question).

But, it's radioactive. One way to shield people from the radiation, but allow the heat to come out of it, is by enclosing it in lead glass. This glass would block most of the radiation, with the added benefit of being very pretty.

Mineral life.

http://theminiaturespage.com/boards/msg.mv?id=258337

Your energy is life energy. It stands to reason that something with a lot of it is alive. It might not be alive in the way we think of life. It might actually be more alive than that.

Depicted - the Horta and its eggs, from the Star Trek episode The Devil in the Dark. The Horta is a silicon life form living deep in tunnels. The valuable and useful "crystals" found by human colonists turned out to be its eggs. The Horta protected its eggs.

So too your "ore". The deep world is vast - much larger than our two dimensional surface shell. This subterranean realm is full of living things, sparking with life energy. These things are very different from the surface life we are familiar with. The ore are tendrils, or twigs, or spores, or possibly even eggs from creatures that live deeper down. Taken from their habitat, they slowly die as their energy radiates away with no prospect of replenishment from the earth.

For the surface life, these crystals are useful and beautiful. Those that use them might realize they slowly wane and go out, but might not realize they are dying. Some specimens of this "ore" might be able to try to escape, or find other sources of life energy. Some might have a Horta equivalent - a parent or patron interested in saving them or preventing future abductions.

I'm going to assume by 'thermal-like' you mean actually thermal energy, and you'll just claim the heat as a side-effect of this new energy type.

The only cases that can 'constantly' emit heat are minerals with high radioactive contents. Those are dangerous of course, but if you can find some way to make them plentiful and say that the native life in this world has evolved natural radiation resistance far better than our own, it might work. Plain mineral forms tend to not emit much heat, but pure forms of some radioactive metals emit so much heat that they glow red-hot (and some simultaneously fluoresce from their own radiation).

Other options that work on much shorter time-scales:

• Minerals which exhibit exothermic oxidation. Pyrite (iron(II) disulfide, also known as fool's gold) is probably the easiest example. Under normal atmospheric conditions, it oxidizes (very slowly) into rust (mostly iron(III) oxide)) and sulfur oxides (mostly sulfur trioxide, which is slightly dangerous as it will produce sulfuric acid in any nearby water). Another reasonably common example is arsenopyrite (iron(II) diarsenide), though that's a bit more dangerous because it produces toxic arsenic compounds when it oxidizes. Both of these produce a small amount of heat when they oxidize. The process can be sped up (and the heat increased a bit) by increasing the surface area of the minerals, or by increasing the humidity of oxygen content of the air they are in.


• Hygroscopic minerals which exhibit exothermic dissolution in water. There are very few of these in real-world geology, all of them are ionic metal salts, and all of them are rare. If you're willing to mess with geology a bit, you could use oxides of alkali-earth metals for this though. Calcium oxide is an easy example, it can easily produce temperatures in excess of 300 degrees celsius while dissolving (enough to things on fire or cause some pretty nasty burns), though it does produce a rather caustic solution of calcium hydroxide (which can easily produce some pretty nasty burns of the chemical variety instead of the thermal variety).


• Fluorescence in the infrared region. Quite literally, stuff that radiates heat when it fluoresces. I don't know of any minerals that exhibit this to any significant degree in real life, but it's been demonstrated in synthetic compounds before. Most likely, it would end up being a case of a mildly radioactive mineral that self-fluoresces, probably with some associated fluorescence in the visible light spectrum too (if you make the visible component narrowband, that could then be the 'color of life' in your world).

Of course, you could also just pick a real-world mineral that already meets your other criteria, and just attribute this new effect to it as well. Gemstones may work well for this, because they can then also be processed by your people into nice looking decorations (and that may improve or reduce their ability to emit this life energy), and true gem-quality samples are rare for most of the 'classic' gemstones.

Prasiolite might make an interesting choice if you go with this approach, it has rather beautiful pale green crystals, it's rather durable (it's a particular variety of quartz), it's pretty rare in nature in real life (but your geology could be just different enough that it's more common), and less scrupulous people can produce synthetic prasiolite by heat-treating amethyst. You could have a whole aspect to it where natural samples are far better at producing life energy, so they are significantly more valued, and some countries might have laws against producing and/or selling synthetic specimens.