The following chart represents relative density of a variety of woods.  Cocobolo is the second most dense wood in the world, Ironwood being the most dense of all. 

 

Balsa                        .11

Pine                          .36

Alder                         .38

Redwood                   .40

Cedar                        .42

Mahogany                  .45

Laurel                        .47

Cherry                       .50

Elm                           .50

Fir, Douglas               .50

Magnolia                    .50

Walnut                       .53

Teak                          .56

Goncalco Alves           .56

Birch                          .60 

Maple                        .63

Beech                        .64

Oak                           .65

Rosewood, Bolivian    .71

Rosewood, E. Indian  .78

Water                      1.00

Cocobolo                 1.10

Ironwood                 1.30