Hello Kirt
That is exactly where my Grandmother found this rock (north shore)while on a car trip years ago. She brought many others home but this was the most interesting. I have never tried polishing it. That is it's natural weather worn surface.
The black layer attracts a rare earth magnetic quite strong. The same magnets seen in the other r?o?c?k you commented on. I don't know what type of rock, crystal or mineral it is. I found it while walking my dog. I have walked the same path for nine years and find something unusual from time to time.
I have studied the surface closely and I do not think it is man made glass, it is mineral of some sort. The magnetic quality is puzzling. It sent me on a research quest for magnet 'attracting' minerals. Alot of what I found was over my head, when all I wanted to know was whether something attracted a magnet or not and why. The dull grey colour doesn't match any thing.
The magnet attracting quality brought me round to meteorites and tektites, which tend to have this quality. Which is exciting because I have found other "things" that look like something...well I am not sure what but...ya never know.
Someone asked about my jewellery...Yes I design and make it myself. I have a post secondary education in jewellery design and fabrication from OCAD in Toronto, ON Canada.
I originally came to Canadian Rockhound to find out what the unusual rocks I was finding might be. I found a whole country worth of 100% Canadian gems and every day people finding them. It is a homey little site and sometimes quiet. I have some new photos of some silver I am working on.