Hey folks this came from the Encylopedia of Arda marbe this will answer your question more clearly.
When Sauron chose the land of Mordor as his dwelling-place in the Second Age, Orodruin was the reason for his choice. He 'used the fire that welled there from the heart of the earth in his sorceries and his forging' (from Of the Rings of Power and the Third Age); the most famous result of his forging, and in fact the only one we know of for sure, was the One Ring, made in about the year II 1600. So powerful was the sorcery used in the making of the Ring that it could not be unmade, except by casting it back into the same fire that had forged it.
Hope that does it. So the ring was a combination of magic and earth's fire and so on... wild uh? :)