Your stone looks like a limestone/quartzite complex. You're in the right part of the country for it to be local. There's a band of limestone and quartzite that comes up the eastern foothills of the Appalachian chain through central Maryland and central/southeastern Pennsylvania. The limestone is from the ancient seabed deposits and the quartzite is from the last time North America bounced off the European and African continents creating the Appalachian chain. (If I remember my Earth Sciences and Paleo classes correctly.)
You may get some buffering or pH reaction from the stone. Easiest way to tell is put a piece in a bucket and pour some vinegar on it to test for bubbling.