#phenocrysts — Public Fediverse posts
Live and recent posts from across the Fediverse tagged #phenocrysts, aggregated by home.social.
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Quincy or #BlueHills #Porphyry #Granite
An alkaline, nonorogenic granite intruded into #Avalonia in the #Silurian / #Ordovician as it cruised from peri-#Gondwana to #Laurentia, before assembling #Pangea in the #Acadian #Orogeny (#Devonian). It’s coarse, with the #phenocrysts of amphiboles(?) (possibly riebeckite?)…I’m no petrologist. From@the Eaton’s Pond conservation area@at the #Braintree #Quincy border. My photos.
#geology #igneous #Massachusetts #Boston #NewEngland #Fujifilm #photo