#Mafic enclave (?) in Rattlesnake Hill #Granite, #Massachusetts

This Devonian granite intrudes #Proterozoic Dedham Granite south of #Boston. It is younger than the nearby Blue Hill Granite Porphyry. The triangular area is rich in large crystals, possibly hornblende. The blue crystals at lower left may be #riebeckite, another amphibole. Riebeckite gives Quincy Granite and the #BlueHills Range their distinctive color. All on Avalon terrane, out of Gondwana. Acadian Orogeny was Devonian. My #photo

Now the more #riebeckite facies of the #Paleozoic #Quincy #Granite

The Quincy granite was a prized architectural stone, most famously used in the #BunkerHill Monument in #Boston #Massachusetts. Current dating suggests it was intruded into #Avalonia before it glommed onto #Laurentia as #Laurasia and #Pangea were assembled. Today’s #photo set comes from a walk around the eponymous Bunker Hill Quarry. I’ll post more about the history later. Captions!
#Fujifilm #XH1 #igneous #intrusive #NewEngland