A mixture of four parts olibanum, two parts storax, and one part lignum aloes. If the last ingredient is unavailable, then cedar, rose, or citron will suffice. These must be turned to fine powder. Although many sources give frankincense as another name for olibanum (and that's what you get when you buy it), they are actually two different species of the genus Boswellia in the Burseraceae family. Due to their similarity, however, either can be used.