Purple Crystal Dust

The purple dust blown from the Plains of Purple Dust is highly magically charged and reactive, to the point that inhaling it can result in cases of glitterlung, where first the sufferer's lungs, and then eventually their whole body, is converted into more of the magical crystalline powder.
Despite the immense danger of the dust, the sheer arcane power imbued into it makes it an immensely useful reagent for both arcanists and alchemists. Heavily masked gatherers make dashes across the border from the desert proper to gather as much of the crystal powder as they can carry before racing back ahead of the storms of wild magic and the walls of wind-borne dust which can sweep across the plains in moments. The deeper they can penetrate, the more pure and powerful the dust will be, uncontaminated by normal sand and without its energy expended in reactions with normal matter; but the greater the risk they will be unable to escape before they are turned to crystal themselves.
Dust gatherers are frequently caught in the unpredictable storms which can rise out of nowhere in moments, and many never make it back. Some do not manage to mask tightly enough, and they and their compatriots must race to reach magical healing before their lungs are so far converted into the purple crystal that they die. Some report seeing strange crystalline shapes moving within the gloom of approaching duststorms.
The crystal is the result of a self-sustaining reaction between magical weapons utilised eons ago by two warring kingdoms neighbouring one another. The clashing magic turned everything it touched into highly-charged, magically-reactive crystal - before the fragile crystal shattered, expending its energy on gradually turning everything it touched into more of the same crystal, which shattered into dust in turn, to continue the process. Both organic and inorganic materials are affected; while beings are rarely exposed to enough of it, for long enough, to be at great risk, the disease known as Glitterlung is the result of the fine powder settling into the lungs.
Resting undisturbed in contact with the tissues of the lungs, the crystal gradually converts the lungs into more of the same. The charged particles sparkle and flash in the light as they are exhaled, as the first sign that a sufferer has been exposed; if they do not receive healing magic in short order, it will soon be a contest whether they will suffocate, bleed to death within their lungs, or drown in their own blood.