Michael : you had a question sent in by Dustin that you answered on May 23, 2010 about a red rock - Dustin had submitted a picture of his rock. I found 3 rocks yesterday in my yard that I believe a "mole" had dug up - anyway, my rocks are much brighter red and more polished than the pictures that Dustin submitted. I did not see an answer to his question as to the type of rock he found. Can you enlighten me as to what I may have come accross as I have never seen such a color of a rock before
Thanks for writing, sounds like some interesting rocks you have found.
You are lucky in that Pennsylvania has a great geological survey - the link below has surface geological maps by County and a link to detailed descriptions of the lithology. This should help to narrow things down.
On the other hand Pennsylvania along with much of the Midwest is overlain by glacial deposits which are notably complex and contain a wide variety of minerals. Red stones usually indicate the presence of iron. But as you'll find iron can be present in many different rock types and mineralogies. The second link is the rock type ID tool I sent to Dustin.
Based on color alone it may be a sandstone or a shale per the glossary on the PA DCNR page.