Reference Document - MCU24/0143 (As Published)

                                                                                        METHOD OF ROCK DESCRIPTION
                                                                                                     USED ON LOGS

             CLASSIFICATION AND INFERRED STRATIGRAPHY
             Rock is classified and described in borehole and test pit logs using the preferred method given in AS1726 – 2017.
             The material properties are assessed in the field by visual/tactile methods.

             STRENGTH
                                                 Point Load
                Symbol             Term         Index, Is(50)                                       Field Guide
                                                   (MPa)
                   VL              Very         0.03 to 0.1       Material crumbles under firm blows with sharp end of pick; can be peeled
                                   Low                            with knife; too hard to cut a triaxial sample by hand. Pieces up to 30 mm
                                                                  can be broken by finger pressure.
                    L              Low           0.1 to 0.3       Easily scored with a knife; indentations 1 mm to 3 mm show in the specimen
                                                                  with firm blows of pick point; has dull sound under hammer. A piece of core
                                                                  150 mm long by 50 mm diameter may be broken by hand. Sharp edges of core
                                                                  may be friable and break during handling.
                    M            Medium           0.3 to 1        Readily scored with a knife; a piece of core 150 mm long by 50 mm diameter
                                                                  can be broken by hand with difficulty.
                    H              High              1 to 3       A piece of core 150 mm long by 50 mm diameter cannot be broken by hand but
                                                                  can be broken with pick with a single firm blow; rock rings under hammer.
                  VH               Very           3 to 10         Hand specimen breaks with pick after more than one blow; rock rings under
                                   High                           hammer.
                  EH            Extremely            >10          Specimen requires many blows with geological pick to break through intact
                                  High                            material; rock rings under hammer.
             Relationship between Is(50) and UCS (unconfined compressive strength) will vary with rock type and strength, and
             should be determined on a site-specific basis. UCS is typically 10 to 30 x Is(50), but can be as low as 5.

             ROCK MATERIAL WEATHERING
                 Symbol                      Term                                                   Field Guide
                                                                  Soil developed on extremely weathered rock; the mass structure and
                                            Residual
                    RS                                            substance fabric are no longer evident; there is a large change in volume
                                              Soil                but the soil has not been significantly transported.
                                          Extremely               Rock is weathered to such an extent that it has soil properties - i.e. it either
                   EW
                                          Weathered               disintegrates or can be remoulded, in water.
                                                                  Whole of rock is discoloured, usually by iron staining or bleaching to the
                                                                  extent that the colour of the original rock is not recognizable. Rock strength
                                    Highly
             HW                                                   is significantly changed by weathering. Porosity may be increased by
                                   Weathered
                                                                  leaching, or may be decreased due to deposition of weathering products in
                                                 Distinctly
                         DW                                       pores.
                                                 Weathered
                                                                  Whole of rock is discoloured, usually by iron staining or bleaching to the
                                   Moderately                     extent that the colour of the original rock is not recognizable; but shows little
             MW
                                   Weathered                      or no change of strength from fresh rock.

                                           Slightly               Rock is slightly discoloured but shows little or no change of strength relative
                   SW
                                          Weathered               to fresh rock.
                    FR                       Fresh                Rock shows no sign of decomposition or staining.
             ABBREVIATIONS FOR DEFECT TYPES AND DESCRIPTIONS
            Defect Type                                         Coating or Infilling                    Roughness
               CS/CZ    Crushed seam/zone (Fault)                 Ca     Calcite                          Po      Polished
               DB       Drilling break                            Clay   Clay                             Sm      Smooth
               EW       Extremely weathered seam                  Cn     Clean                            Sl      Slickensided
               HB       Handling break                            Co     Coating ( > 1mm)                 Ro      Rough
               IS/IZ    Infilled seam/zone                        Fe     Iron oxide                       VRo     Very rough
                                                                  Op     Open
               J        Joint
                                                                  Qz     Quartz
               Pt       Parting                                   St     Stain                         Planarity
               SS/SZ    Sheared seam/zone (Fault)                 Vn     Veneer (<1mm)                    Cu       Curved
               Vn       Vein                                      X       Carbonaceous                    Dis       Discontinuous
                                                                                                          Ir       Irregular
                                                                                                          Pl        Planar
                                                                                                          St        Stepped
                                                                                                          Un        Undulating
                                                                                                                                              Rev5
                                                                                                                                        August 2024
Document Set ID: 24125427
                  24010296
Version: 1, Version Date: 17/09/2025
                          07/08/2025