I'm not as familiar with the more exotic woods used for fingerboards, traditionally in the Double Bass world, where I'm also very involved, Ebony, Rosewood, and Maple were used for fingerboards. Since both Ebony and Rosewood
are quickly becoming endangered hardwoods, Taylor guitars has stepped in and is helping with management and conservation efforts of those forrests. What they were doing was felling trees that had white specks in the ebony and
rejecting them for sale to manufactures, simply discarding all the wood that wasn't perfectly black. Wenge is also likely an endangered hardwood and could be possibly more scarce. Hopefully we won't reach the crisis that Grenidilla did
with woodwind manufacturing, where they actually had to go to synthetic materials for the upper portions of a clarinet, but we already may have arrived at that point with Ebony, Rosewood, and possible Wenge.