a Canada stone (which might be a Hindustan stone, but is labeled as Canada stone)
This is very cool.
The fact that you found that in Canada basically puts paid to my theory that Canada (oil)stones were Hindos rebranded for export, because TH&Co. were a company in London. Finding a 'Canada Stone' in Canada, but branded for a UK company, makes it pretty much a racing certainty that these stones aren't Hindos in disguise.
Here's some info about the company from Neil M: