Malachite is copper hydroxyl carbonate with a hardness of 3.5-4. It is an opaque mineral, most commonly found in mass rather than crystalline form and best known for its unusual designs, especially the "bullseye" concentric circles. Its density makes it useful to absorb negative energy. It's commonly found in Zaire, Africa. The name comes from the Greek malache "mallow" in reference to green leaf color.