Ultrapotassic igneous rocks are a class of rare, volumetrically minor, generally ultramafic or mafic silica-depleted igneous rocks.
While there are debates on the exact classifications of ultrapotassic rocks, they are defined by using the chemical screens KO/NaO > 3 in much of the scientific literature. However caution is indicated in interpreting the use of the term "ultrapotassic", and the nomenclature of these rocks continues to be debated, with some classifications using KO/NaO > 2 to indicate a rock is ultrapotassic.