Returning Frankie's Rocks

I have wanted to read this book for about ten years, I remember a local paper article about the author Dana Hornig coming to Colchester to return a piece of stone that had come from the roman wall, I think by the Balkerne Gate. Years after his mothers death he found she had a hidden collection of rocks and stones labeled with where they came from when his family relocated to England, the book is about him returning them! I love a good travelogue filled with self discovery!