While I boil all driftwood before using, mopani wood in particular is high in tannins, and therefore boiling will not prevent the wood from coloring your water somewhat. Aquarium water may appear a tea-like color, and while some believe the tannins discolors the water, some aquarium enthusiasts prefer a more natural look, often the darker the better. In addition, tannins are quite beneficial for many types of aquatic life and often people will use the boiled water from catappa leaves (or the leaves themselves) for the same health benefits or looks.
Boiling process and tannins
Living Art NC - Durham, NC 