Wikipedia
Thermopotash
ThermoPotash is a slow-release, multi- nutrient fertilizer product made from a silicate-based potash resource. It contains on average 4%-14% KO. It is derived by performing a pyrometallurgical process on Verdete (green) slate rock and limestone.
ThermoPotash is being developed as an alternative to current potash sources, such as potassium chloride (KCl) and potassium sulfate (KSO).