Holknum

Although Holknum goes by many names, it is unanimously described as a dull, grey material which looks almost like it has a powdery texture, and which has the consistency of very sandy clay. When dug up, the ore must be concentrated and the unusable parts of it must be separated. Roughly only 5% of a vein will be the actual yield of holknum once it's gone through separation and concentration.
Veins of the ore are constantly radiating an energy which has been shown to be wave-based and as a result of a magical fusion. The waves are dangerous, and can cause bodies to shrink in some places rather eratically, causing death in those affected; even when not in the presence of Holknum, this effect has a half-life of several days, meaning that it can cause whatever has been affected by it to also spread the dangerous waves for a period of time, while still harming the victim affected.
In order to prevent holder death, bulky "Null-Suits" have been created in different fashions. These are suits made from magic-resistant materials, usually some kind of stone which can be easily chipped into the pieces required for the suit, such as soapstone, limestone, and occasionally harder stones with greater magic resistance such as granite. The stones near-perfectly reflect any waves sent towards the wearer, however there must be some form of seeing for the miners, which can lead to blindness as the eyes must be exposed to see what the miner is doing. Research is currently being made into greater forms of magic protection.
It is known the drow mine with unheard-of efficiency due to their lost elven mining tech. It is believed they use a machine interface to cut the exposure time to a minimum, however, this technology has not been replicated yet, as the drow are ever reclusive in the Undercold. The Melange use amalgam slaves in order to bypass the problem, and Kinnek have strict laws and regulations surrounding safe practices so as to ensure the happiness of its citizenry. It is believed that gnomes use or are researching forms of indirectly viewing the ore; modelling the elven method of utilizing magic to view the ore through their suits.
Casting in the presence of holknum causes spells to fail or cascade into a benign spell, however druids and rangers are particularily trained to use the power of holknum to power their own spells -- working with the tide rather than against it. Druidism is the art responsible for manipulating flesh and even creating new species (such as the melange and amalgams). Any druid can attempt to create life or polymorph creatures permanently, however any druidic act loses it's intended efficiency as the spell deteriorates, and the result can lead to malignant growths which can kill the flora, fauna, or person effected by the spell. It is for this reason that many widely known spells have an integrated 'self destruct' feature to revert their changes to prevent long term damage. Only the most skilled druids can cause permanent change without destroying their canvas over time, an effect that the amalgam people constantly suffer from. The strength of these magics absolutely require the powerhouse material holknum in order to function.
Holknum is contained in 'coffins' (so named for the unreliability of them leading to casualties, as well as their rectangular shape, openable lid, and stone composition making them seem like coffins) after it has been mined so as to keep the effects contained. The intense labour required in the mining of holknum, as well as the dangers associated with it and the intense cost of materials means that many "Mining Outfits" have cropped up, which function similar to unions in real life, but focus on travelling nationwide in order to profit as a group from mining towns. All these factors cause holknum to be priced incredibly high, leading to a gold rush whenever holknum is discovered.