You can find materials, or find objects that use a material, in several different ways.
Finding and Selecting Elements that Use a Material
To find and select all objects and clusters that use a material
In the material manager, right-click on a material's shaderball and choose Select Objects with this Material.
In a render tree view, right-click on a Material node and choose Select Objects with this Material.
Select one or more materials, and choose Materials 
Select Objects from Material in the material manager.
Select one or more materials, and click the Who Uses? tab at the bottom of the shelf in the material manager. Doing this doesn't select the objects that use the material, but simply lists them in the panel below the shelf. You can then easily select the objects from this list.
Highlighting Materials Used by Selected Objects
You can quickly find out which materials are being used by selected objects in a scene.
To highlight materials used by selected objects
Click the Highlight Materials From Selected Objects icon in the material manager's command bar, or choose Materials Get Material From Selected Objects.
All materials that are used by those objects are highlighted in the material manager's shelf area.
If desired, set the material manager's display filter to Highlighted Materials to display only those materials.
Picking Materials from an Element
You can also select materials on a scene element by using the Pick Material from Object tool in the material manager.
To select a material from an object or cluster
Click the Pick Material from Object Tool icon or choose Materials Pick Material from Object Tool in the material manager.
Click on an object. The material applied to the object or cluster (as appropriate) is highlighted and selected in the material shelf.
The tool stays active. Click on another part of the object, or select another object using supra mode.
To exit the tool, activate another tool in sticky mode or press Esc.
To select materials from multiple objects or clusters
You can also use the Pick Material from Object tool to select materials from multiple objects or clusters (such as having different materials on several polygon clusters on one object) in your scene. For example, if you had a character in your scene with multiple materials, you could find out the name of the material for the arm, the one for the torso, and so on.
Select multiple objects or select an object that has multiple materials on its clusters.
Activate the Pick Material from Object Tool.
Click and drag the mouse across the objects.
The name of the material for the object that is currently under the cursor is displayed in the viewport as you do this.
When you find the material that you want, release the mouse. The material is selected in the material manager.
