These stones from just east of Algonquin Park are 100% granitic gneiss - forged in the dawn of our planet, warped one billion years ago in a mountain-building event, and shattered by glaciers into the smooth river rock we sell today. Even at the 1/4 inch size, these stones still display patterns of microcline feldspar, muscovite mica, and classic milky quartz. Beautiful when wet, these stones are useful for planters, water features, landscaping, and more!