kyanite crystals in quartz - São José de Safira, Minas Gerais, Brazil - hand/display specimen the swallowtails

the swallowtails

If tiny rhombs would be useful in your classroom

It would be instructive for students to compare these two dune sands - both fine-grained but very different in color

Tuffs are light colored

Note that these have been affected by covid

kyanite crystals in quartz - São José de Safira, Minas Gerais, Brazil - hand/display specimen the swallowtailskyanite Al2SiO5 Kyanite forms when aluminum rich rocks are metamorphosed, and is frequently found in schists that formed at medium to high pressures and lower temperatures in areas of regional metamorphism. At higher temperatures, kyanite converts to sillimanite. Occasionally the metamorphism produces a pegmatite with large crystals that form when a fluid rich magma allows rapid movement of atoms. These large crystals of kyanite and the surrounding