public void GetInfo_FamilySymbol(FamilySymbol familySymbol)
{
    string message;
    // Get FamilySymbol family name
    message = "Family name is : " + familySymbol.Family.Name;

    // Get FamilySymbol material
    message += "\nFamilySymbol materials are :";
    foreach (ElementId matid in familySymbol.GetMaterialIds(true))
    {
       Material material = familySymbol.Document.GetElement(matid) as Material;
       if (null != material)
       {
          message += "\n" + material.Name;
       }
    }

    TaskDialog.Show("Revit",message);
}

Public Sub GetInfo_FamilySymbol(familySymbol As FamilySymbol)
   Dim message As String
   ' Get FamilySymbol family name
   message = "Family name is : " & Convert.ToString(familySymbol.Family.Name)

   ' Get FamilySymbol material
   message += vbLf & "FamilySymbol materials are :"
   For Each matid As ElementId In familySymbol.GetMaterialIds(True)
      Dim material As Material = TryCast(familySymbol.Document.GetElement(matid), Material)
      If material IsNot Nothing Then
         message += vbLf + material.Name
      End If
   Next

   TaskDialog.Show("Revit", message)
End Sub