If you ask me, it almost looks like a type of limestone. I would as other people suggest make sure it is washed thoroughly. I would then give it an acid test to see if it reacts. I test with muriatic acid, but you could use vinegar but it will take longer for the bubbles to show. Acid test should be done on a discrete freshly exposed surface of the rock.
If it reacts to the acid test then it contains some carbonates and will react with your water. Then you have a choice of whether to use it in the tank, it will increase your hardness and along with it the pH, but if you already have a hardwater tank that will not be an issue. In practice I find if you do large changes frequently you can use limestone in softwater tanks too, but you cannot skip on your water changes.
If you have a tighter location on where you collected the rock one might be able to limit the choices of rock types as well, Canada is very diverse with rock types. Also close up photos would be helpful, close enough to see crystals in the rock if there are any.
If you collected the rock from an arid region you need to be a bit more careful, sometimes in these areas the rocks can get coated with various minerals which can cement onto the rock, some which can be toxic, ie Arsenic.