Help identifying stone with masonic symbol carved into it..?

Question:

Help identifying stone with masonic symbol carved into it..?

We found a squarish stone in an old barn on our property that has the masonic symbol carved on top of it. Looks like marble maybe (little-to-no grain and white) and it's about 2" thick and about 8" square. The barn hasn't been used since the early 1900's but the carving could have been put there as late as the 1980's maybe. How can I determine if it's marble and what its value may be?

Best Answer - Chosen by Asker:

A few drops of hydrochloric acid on the reverse will tell you. If it's marble, it will fizz. You might want to try to research previous owners of the farm. Could be one was a mason. The stone was probably a cornerstone for the barn itself or perhaps another farm building that may no longer be there. Chances are it's not worth much, but try a local antique dealer to be sure.