“And that brings us to our next item, gentlemen.
This unusual metal is called Mirichromite, and has a single, very interesting and useful property.
Here I have a large sample of this material, fashioned into a drinking goblet. Note it’s dull, blue color.
Now, as I bring it near this enchanted helmet, do you see the change? Note how the goblet lightens in shade as I bring it closer?
What is especially interesting is that it accomplishes this without radiating magic in turn. This is easily demonstrated with a second such goblet. If this material changes color in presence of magic, if this itself were magical in nature, it should activate itself, or other samples of the same material. But no- as you see, they only change color from other magic, not themselves.
Now, before you say ‘What if the magic of the material is simply weak’ I can tell you that direct detection of magic is fruitless - the very act of casting any spell on this material will cause the color change.
Exerpt from the Proceedings of the Arcane Academia, Volume VII ic2.
A lively exchange followed on the philosphy of what is and is not magic…
Mirichromite appears most commonly as a soft, blue-grey metal with structural properties nearly identical to silver, with the exception it does not tarnish. It is dull and is generally matt in aspect.
It’s most remarkable property is that it changes from blue-grey to blue to white in the presence of magic, the lighter the color, the stronger the magic. This behavior is similar to Thermochromatic dyes(materials that change color in response to temperature variation.)
Coupled with it’s matt surface, Mirichromite close to a powerful magic source appears more as pale ivory then a metal.
What makes this material useful and interesting is that this property is the material’s response to magic, and is not magic in itself. This is similar to magical fire starting mundane ones.
None save the gods know the origin of this metal. It is found generally in the same ores as silver and until it’s special properties were discovered, was considered a byproduct. With similar workability to silver, it was often made into simple implements such as cutlery, combs and other items not requiring high mechanical strength.
It’s special property was discovered when magic began to be used more extensively in the silver mining process - when spells to help extract or find silver were used, the color change of various Mirichromite items was noted.
There is an even more rare variant of this metal which will actually glow in there presence of magic. This is a physical process similar to that displayed by lightning bugs and certain fungi. The light produced is invariably white.
There has been some study into the possibility that this phenomena is bi-directional in that if a sufficiently bright source of light could be used, that this type of Mirichromite might produce magical emissions. However, since no suitable light-source has been found, this is still only a theory.
This material can be combined in alloy with other materials to improve it’s physical strength, especially with copper. The Mirichromite/copper alloy has properties similar to Electrum, although it’s color changing or light emitting properties are directly affected by the ratio of Mirichromite to base metal.
If the technology is available, electroplating is the most effective means to provide structurally sound items with the color changing or light-emitting properties intact.
Use of the color-changing form is limited primarily to magic detection devices or for novelty purposes.
Casting wands are commonly tipped with this material - they can be used to detect magic, and will change color also when used to help cast spells.
Minor magical devices which serve to ease the casting of spells, usually by simplifying the somatic(gesture) component. In some cases, more powerful Casting Wands can lend power to the user and increase the effectiveness of the spell.
Another use is to make stoppers for magical potions intended for long-term storage. As the potency of the potion degrades over time, the color of the stopper will fade.
The very rare variant which actually radiates light is more useful in the creation of magical devices. It provides greater feedback for detection, and can serve as light sources when combined with some item of magic. This would allow, for example, cursed items to have some utility.
Enchanted items can be inlaid with this material to provide interesting visual effects, especially if gemstones, colored glass or crystal is laid over-top the material.
Persons with a large quantity of either material could inlay floor tiles. The tiles then could be used to show passage of unseen magic-using entities.
Though strongly related to Silver, Mirichromite does not occupy the vaunted station of it’s brighter sibling. It is not considered one of the seven metals of alchemy (gold, silver, mercury, copper, lead, iron & tin).
Alchemists who have experimented with the material have found that it seems to have affinity to chimera, and a celestial relationship to comets and other erratic bodies.
Additional Ideas (3)
These useful items are small metal balls plated or otherwise coated with a thin layer of mirichromite and polished smooth. Bright Mirichromite is by far the best type for this application.
When thrown on the ground they can be used to indicate the location of magical traps, or can serve to show if magically invisible entities pass through the marble-field.
In worlds where this metal can be found, use of it to produce devices 'certified' against magical influence would be common. To prevent magical tampering with scales used by merchants, it may be mandated that scales be made or at least coated with such a metal. This of course does not prevent more mundane forms of tampering, but should prevent use of invisable weights.
Worn by a king, noble or just someone with a reason to fear the magic users, it changes colour when a wizard, witch, shamen or magical creature is close by, allowing the wearer to take evasive action or prepare for combat.