A triangular diagram with SiO2, Al2O3, and H2O+fluorine on the vertices. Minerals with compositions that fall within the triangle are labelled, including kyanite, topaz, and zunyite. From Mark Barton (1982), American Mineralogist

The organizers of #MinCup25 are very clever. Today and yesterday feature three aluminosilicates that are compositionally co-linear!

Diagram from Barton (1982), published in the American Mineralogist.

#kyanite #topaz #zunyite #aluminosilicate #MineralSocAmerica #ArgillicAlteration