Agrellite () is a rare triclinic inosilicate mineral with four-periodic single chains of silica tetrahedra.
It is a white to grey translucent mineral, with a pearly luster and white streak. It has a Mohs hardness of 5.5 and a specific gravity of 2.8. Its type locality is the Kipawa Alkaline Complex, Quebec, Canada, where it occurs as tabular laths in pegmatite lenses. Other localities include Murmansk Oblast, Russia, Dara-i-Pioz Glacier, Tajikistan, and Saima Complex, Liaoning, China. Common associates at the type locality include zircon, eudialyte, vlasovite, miserite, mosandrite-(Ce), and calcite.
Agrellite displays pink fluorescence strongly under shortwave and weakly under longwave ultraviolet light. The fluorescent activator is dominantly Mn<sup>2+</sup>, with minor Eu<sup>2+</sup>, Sm<sup>3+</sup>, and Dy<sup>3+</sup>.
It is named in honor of Stuart Olof Agrell (1913âÂÂ1996), a British mineralogist at Cambridge University.