Karri (Eucalyptus diversicolor) is a very large tree limited to southwestern Australia.
Karri resembles jarrah (E. marginata) in structure and general appearance. It is usually paler in color and, on average, slightly heavier (913 kg/m3 (57 lb/ft3)) at 12% moisture content. Karri is a heavy hardwood with mechanical properties of a correspondingly high order, even somewhat higher than that of jarrah. The heartwood is rated as moderately durable, though less so than that of jarrah. It is extremely difficult to treat with preservatives. The wood is fairly hard to machine and difficult to cut with hand tools. It is generally more resistant to cutting than is jarrah and has a slightly more dulling effect on tool edges.
Karri is inferior to jarrah for underground use and waterworks. However, where flexural strength is required, such as in bridges, floors, rafters, and beams, karri is an excellent wood. Karri is popular in heavy construction because of its strength and availability in large sizes and long lengths that are free of defects.
*Much of the base wood information presented here is made available by the USDA FPL FS. If you are interested in a much more technical description of wood properties, I encourage you to visit the source.