Join Date: Feb 2013
Location: santa paula, ca, United States
If you see bubbling, foam, then the rock has carbonates which could change your water. Vinegar doesn't always work, try scratching the rock with a knife, if you can't scratch it then it is probably not a carbonate rock. If you can scratch it, try the vinegar on the powder from the scratching, that is a more sensitive test. Or use the nitrate solution mentioned above.