Hard to tell precisely from the pictures. I see some areas that look like calcite. (check hardness with knife or steel nail) The other white mineral could be prehnite, which is sometimes that color in Connecticut traprock.
It's the site of the Duncan Donuts next to the Wendys. You are right it is the Berlin Turnpike. They were blasting the basalt to create more site. I suggest as you are driving keep an eye out for construction sites where they are blasting rock.
These were found in 2008. I don't think there is anything to collect unless you want to hammer the rock walls.