Magnetite is a very common iron oxide mineral. It is found in igneous, metamorphic and sedimentary rocks. It is also the mineral with the highest amount of iron magnetite crystals, which typically occur when the earth's magma cools at a slow enough rate for crystals to form and settle outside the magma.
These earrings just make me feel "natural!" I bought the second pair because I loaned my first pair to a gal getting married in Hawaii and thought she should keep them and, she too, loved the gift!