Dexpan Expansive Demolition Mortar for Concrete and Rock Crushing is the most economical and user-friendly method of breaking large rocks into small pieces. I used it to smash large granite boulders. The hardest part, literally and figuratively, was drilling holes. It's the quartz content in granite that makes it one of the hardest rocks on earth and it takes a long time to drill 19 1 1/2 inch holes into it. Use a paint spatula in a drill and stir until it was the consistency of thick oil or watery cement. It's thick but still needs watering. If you follow the mixing instructions, it's perfect. Pour the mixture into the hole and come back in a day or two and you'll be amazed at the results. The Dexpan works by expanding the material in the hole in the same way the timers of old used ice, but with much more force. My job site was 20 feet from my neighbor's house and he didn't know what I was up to, it would have been more obvious if I had used explosives or a jackhammer!