This property returns the physical material from which the instance is made.
Assembly: RevitAPI (in RevitAPI.dll) Version: 2015.0.0.0 (2015.0.0.0)
Values of this property can be Steel, Concrete, Wood or some other material. Different from Revit materials that geometry really consists of, this property is a family parameter defining family behavior and can not be set per instance. Its value is the same with the type of the instance's family. For example, the instances of different kind of column families(Steel, Concrete or Wood) have different material values and can't be changed int the UI or RevitAPI.