John Faithfull🌍🇪🇺🏴󠁧󠁢󠁳󠁣󠁴󠁿🧡 ✊🏼✊🏿Jul 25, 2023
#DogWalkingGeology from this morning. Here's a lovely wee layer of pale blue elongate kyanite crystals, pale pink elongate andalusite, plus some wee brown round garnets, in schist from Ardalanish Bay. Although the andalusite and kyanite look happy together, they are not actually in equilibrium: this layer has "frozen" during the slow process of converting kyanite to andalusite. Reactions are all about the kinetics! #Metastable #Mull #Moine #RossOfMullGranite #Geology #Minerals #Al2SiO5 #Kinetics
Show threadVicky Veritas
@FaithfullJohn Fascinating, John! Thank you!
Jul 25, 2023 at 2:17pmWeb
Show threadJohn Faithfull🌍🇪🇺🏴󠁧󠁢󠁳󠁣󠁴󠁿🧡 ✊🏼✊🏿Jul 25, 2023
@vickyveritas This locality is just sooooo good! You can see in the pic that many individual crystals are part-kyanite and part-andalusite, which is just 🤯 🤩 🥰 More on this in John Wheeler's paper https://academic.oup.com/petrology/article/45/4/835/1529671
Disequilibrium in the Ross of Mull Contact Metamorphic Aureole, Scotland: a Consequence of Polymetamorphism

Abstract. The Ross of Mull pluton consists of granites and granodiorites and intrudes sediments previously metamorphosed at amphibolite facies. The high grade a

OUP Academic
Show threadVicky VeritasJul 25, 2023
@FaithfullJohn This is awsome! Thank you for the link to the paper!