My sister saw a quote for $85 per ton. How much would one of these weigh? One big enough to put close to the fire and sit on. She is close to Montreal, if you happen to have any specifics about there. Thank you so much.

You can figure out the weight using the average density of granite which is 2.75 g/cm3.

You can use Online Conversion - Convert just about anything to anything else for help.

Figure out about how big: l x w x h all in centimeters to get cm^3 and multiply this by 2.75 to get the number of grams.

Then convert grams to whatever version of tons you use.