These are generally up to 2 inches. Thin up to 3/8 inches thick. Not polished on the back. "Gabbro is a phaneritic, mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is chemically equivalent to rapid-cooling, fine-grained basalt."