Aluminoceladonite is a low-temperature potassium dioctahedral mica mineral which is an end-member in the illite-aluminoceladonite solid solution series. The chemical formula for aluminoceladonite is K(Mg,Fe<sup>2+</sup>)Al(Si<sub>4</sub>O<sub>10</sub>)(OH)<sub>2</sub>.
Aluminoceladonite is often referred to as a rare mineral, though its actual abundance may be underestimated due to difficulty of identification. Aluminoceladonite, along with other phyllosilicate minerals in the illite-aluminoceladonite solid solution series, has been observed mainly among finely dispersed, mostly inter-layer-deficient, aluminium-rich potassium-dioctahedral mica varieties occurring in sedimentary rocks.