Sunleaves Rocks are a reusable growing medium with serious H20-holding power for use in any kind of garden. They're made by superheating shale to temperatures up to 2,000 degrees Fahrenheit, rendering them pH-neutral and chemically inert. Gardeners can make their lives a little easier, take care of their plants, and take it easy on the planet when they grow with the rock that doesn't roll! Mined and manufactured in the United States.