Extremely Altered (XA) - AS 1726
Material is altered to such an extent that it has soil properties. Mass structure and material texture and fabric of original rock are still visible.
Comprehensive searchable dictionary of geotechnical terms, classifications, and standards for rock strength, weathering, soil properties, and more.
Comprehensive dictionary of geotechnical terms, classifications, and standards including rock strength, weathering, soil consistency classifications from AS 1726:2017 and CoalLog standards.
Material is altered to such an extent that it has soil properties. Mass structure and material texture and fabric of original rock are still visible.
The whole of the rock material is discoloured, usually by staining or bleaching to the extent that the colour of the original rock is not recognisable. Rock strength is changed by alteration. Some primary minerals are altered to clay minerals. Porosity may be increased by leaching, or may be decreased due to precipitation of secondary minerals in pores.
The whole of the rock material is discoloured, usually by staining or bleaching to the extent that the colour of the original rock is not recognisable but shows little or no change of strength from fresh rock.
The whole of the rock material is discoloured, usually by iron staining or bleaching to the extent that the colour of the original rock is not recognisable, but shows little or no change of strength from fresh rock.
Where it is not practicable to distinguish between Highly Weathered and Moderately Weathered rock the term Distinctly Weathered may be used. Distinctly Weathered is defined as follows: Rock strength usually changed by weathering. The rock may be highly discoloured, usually by iron staining. Porosity may be increased by leaching, or may be decreased due to deposition of weathering products in pores. There is some change in rock strength.
Rock is altered to such an extent that it has soil properties, i.e., it either disintegrates or can be remoulded, in water.
Rock strength and mineralogy usually changed by alteration. The rock may be highly discoloured, usually by iron staining. Porosity may be increased by leaching, or may be decreased due to deposition of weathering products in pores.
Rock is slightly discoloured but shows little or no change of strength from fresh rock. Usually penetrative alteration along defect surfaces.
Degree of alteration not assessed.
Rock shows no sign of decomposition or staining.
Exudes between the fingers when squeezed in hand [Undrained shear strength (su) <12 kPa].
Can be moulded by light finger pressure [Undrained shear strength (su) 12-25 kPa].
Can be moulded by strong finger pressure [Undrained shear strength (su) 25-50 kPa].
Cannot be moulded by fingers, can be indented by thumb [Undrained shear strength (su) 50-100 kPa].
Can be indented by thumb nail [Undrained shear strength (su) 100-200 kPa].
Can be indented with difficulty by thumbnail [Undrained shear strength (su) >200 kPa].
Easily dissociated with flicks of finger nail [Relative density (Dr) <15%].
Easily penetrated by knife blade, readily dissociated by scratching with finger nail [Relative density (Dr) 15-35%].
Penetrated by knife only with firm pressure, readily indented by thumb pressure, dissociated with difficulty by scratching with finger nail [Relative density (Dr) 35-65%].
Difficult to indent by thumb pressure, dissociated readily by knife blade [Relative density (Dr) 65-85%].
Cannot be indented by thumb pressure; Dissociated only by firm pressure with knife blade [Relative density (Dr) >85%].
May be broken by hand and remoulded (with the addition of water if necessary) to a material with soil properties [UCS <1 MPa].
Crumbles under a single firm hammer blow; Can be peeled with a knife [UCS 1-5 MPa].
Breaks under a single firm hammer blow; Scored but not peeled with a knife [UCS 5-10 MPa].
Breaks under 1 to 3 hammer blows; Can be scratched but not scored with a knife [UCS 10-25 MPa].
Breaks under 3 to 5 hammer blows; Hard to scratch with a knife; Can be scratched with tungsten-tipped tool; Hard sound when struck with hammer [UCS 25-50 MPa].
Breaks under 1 hammer blow if resting on solid surface; Cannot be scratched by knife; Scratched with difficulty by a tungsten-tipped tool; Dull ringing sound when struck with hammer [UCS 50-100 MPa].
Difficult to break with hammer even if resting on solid surface; Bright ringing sound when struck with hammer [UCS >100 MPa].
Exudes between the fingers when squeezed in hand [Undrained shear strength (su) <12 kPa].
Su Range: 0 - 12 kPa
Can be moulded by light finger pressure [Undrained shear strength (su) 12-25 kPa].
Su Range: 12 - 25 kPa
Can be moulded by strong finger pressure [Undrained shear strength (su) 25-50 kPa].
Su Range: 25 - 50 kPa
Cannot be moulded by fingers [Undrained shear strength (su) 50-100 kPa].
Su Range: 50 - 100 kPa
Can be indented by thumb nail [Undrained shear strength (su) 100-200 kPa].
Su Range: 100 - 200 kPa
Can be indented with difficulty by thumb nail [Undrained shear strength (su) >200 kPa].
Su Range: 200 - 2000000 kPa
Can be easily crumbled or broken into small pieces by hand.
Relative density (Dr) <15%.
RD Range: 0 - 15%
Relative density (Dr) 15-35%.
RD Range: 15 - 35%
Relative density (Dr) 35-65%.
RD Range: 35 - 65%
Relative density (Dr) 65-85%.
RD Range: 65 - 85%
Relative density (Dr) >85%.
RD Range: 85 - 100%
Material crumbles under firm blows with sharp end of pick; can be peeled with knife; too hard to cut a triaxial sample by hand. Pieces up to 30 mm thick can be broken by finger pressure [UCS 0.6-2 MPa; PLT Is(50) 0.03-0.1 MPa].
UCS 2 - 6 MPa; Easily scored with a knife; indentations 1 mm to 3 mm show in the specimen with firm blows of the 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 [UCS 2-6 MPa; PLT Is(50) 0.1-0.3 MPa].
Readily scored with a knife; a piece of core 150 mm long by 50 mm diameter can be broken by hand with difficulty [UCS 6-20 MPa; PLT Is(50) 0.3-1 MPa].
A piece of core 150 mm long by 50 mm diameter cannot be broken by hand but can be broken by a pick with a single firm blow; rock rings under hammer [UCS 20-60 MPa; PLT Is(50) 1-3 MPa].
Hand specimen breaks with pick after more than one blow; rock rings under hammer [UCS 60-200 MPa; PLT Is(50) 3-10 MPa].
Specimen requires many blows with geological pick to break through intact material; rock rings under hammer [UCS >200 MPa; PLT Is(50) >10 MPa].
Material is weathered to such an extent that it has soil properties. Mass structure and material texture and fabric of original rock are no longer visible, but the soil has not been significantly transported.
Material is weathered to such an extent that it has soil properties. Mass structure and material texture and fabric of original rock are still visible.
The whole of the rock material is discoloured, usually by iron staining or bleaching to the extent that the colour of the original rock is not recognisable. Rock strength is significantly changed by weathering. Some primary minerals have weathered to clay minerals. Porosity may be increased by leaching, or may be decreased due to deposition of weathering products in pores.
The whole of the rock material is discoloured, usually by iron staining or bleaching to the extent that the colour of the original rock is not recognisable, but shows little or no change of strength from fresh rock.
Where it is not practicable to distinguish between Highly Weathered and Moderately Weathered rock the term Distinctly Weathered may be used. Distinctly Weathered is defined as follows: Rock strength usually changed by weathering. The rock may be highly discoloured, usually by iron staining. Porosity may be increased by leaching, or may be decreased due to deposition of weathering products in pores. There is some change in rock strength.
Rock is partially discoloured with staining or bleaching along joints but shows little or no change of strength from fresh rock.
Rock shows no sign of decomposition of individual minerals or colour changes.
Soil developed on extremely weathered rock. The mass structure and substance fabric are no longer evident. There is a large change in volume but the soil has not been significantly transported
Rock is weathered to such an extent that it has soil properties, i.e., it either disintegrates or can be remoulded, in water.
Rock strength usually changed by weathering. The rock may be highly discoloured, usually by iron staining. Porosity may be increased by leaching, or may be decreased due to deposition of weathering products in pores
Rock is slightly discoloured but shows little or no change of strength from fresh rock. Usually penetrative weathering along defect surfaces
Rock shows no sign of decomposition or staining
TBC
TBC
TBC
TBC
White to grey green globular masses or reniform at times with a subfibrous, scaly, or imperfectly columnar structure or as fibrous crusts.
Usually white but can also be colourless, grey, red, green, blue, yellow, brown, orange. White streak, vitreous lustre. Perfect rhombohedral cleavage. Low Mohs hardness (3). Dissolves in cold dilute HCl.
Plant fragments that have undergone some form of coalification.
White in colour. Soft and brittle. Fizzes violently with diluted HCl.
Varying shades of green, yellow, pink - usually lightly coloured. Vitreous to pearly lustre. Perfect basal cleavage. Relatively soft (2-2.5).
Very fine grained sediment with platy minerals. Soft.
Carbon rich mineral deposit formed from the accumulation of organic matter and containing less than 50% ash yield on combustion; coal streaks brown (low rank) to black (high rank) when scratched with a metal tool.
Breccia.
White or slightly tinted. Transparent. Waxy feel with a satiny lustre. Soft (2-2.5). Perfect cleavage.
Umbrella term for the preserved traces or remains of organisms from the remote geological past.
Dark-olive green. Platy-micaceous mineral. Very soft (2). Indicative of shallow marine/coastal shelf environment.
Can be applied to any natural defect except for Broken Zone (BZ) or Coal Cleat (CE). Does not contribute to Rock Quality Designation (RQD).
Smooth but without striations. Reflects light.
Rough to touch. Sandpaper feel.
striations visible on defect surface that may or may not be polished (the angle of the striations to the dip direction of the defect should be noted).
Smooth to feel but not polished or slickensided.
One trough or crest across the core width.
Many sharp troughs and crests in all directions across the core width.
A surface with no obvious curves or irregularities across the core width.
Distinct steps in any direction across the core width.
Rounded crests and troughs in one or more directions across the core width.
Extremely wide defect spacing (<2 m).
Very wide defect spacing (600-2000 mm).
Wide defect spacing (200-600 mm).
Moderately wide defect spacing (60-200 mm).
Moderately narrow defect spacing (20-60 mm).
Narrow defect spacing (6-20 mm).
Very narrow defect spacing (<6 mm).
Increase in grain size in sedimentary rock from base of the bed to its top. Termed reverse grading and is characteristic of some alluvial fan deposits.
Decrease in grain size in sedimentary rock from base of the bed to its top. Termed normal grading and is characteristic of some turbidites and many sedimentary beds deposited in waning flow conditions.
Being positioned between or alternated with other laminations of dissimilar character where the layers are less then 20 mm thick.
Being positioned between or alternated with other layers of dissimilar character.
TBC.
TBC.
Being positioned between or alternated with other layers of dissimilar character where the layers are >200 mm thick.
TBC.
Existing or introduced between subordinate layers of a different type. It applies especially to layers of one kind of material that alternate with thicker strata of another material, e.g., Beds of shell intercalated with sandstone.
Existing with lithology(s) of a different type in no regular fashion and not forming regular structures.
Widely dispersed throughout rock.
TBC.
TBC.
TBC.
TBC.
TBC.
TBC.
TBC.
TBC.
TBC.
TBC.
TBC.
TBC.
TBC.
Visual-Tactile: Behaves as a cohesionless material which may exhibit a dilatancy reaction when shaken but which cannot be moulded into a plastic solid including being rolled into a 3 mm diameter thread. Laboratory: Either or both the Plastic Limit and Liquid Limit cannot be determined by the test methods.
Visual-Tactile: Behaves as a cohesive material but does not exhibit a dilatancy reaction and cannot be remoulded into a 3 mm thread. Laboratory: The Plastic Limit may or may not be measurable but the Liquid Limit cannot be measured by the test methods.
Visual-Tactile: Behaves as a cohesive material, may or may not exhibit dilatancy, and feels smooth but gritty. Dried crumbs are easily broken down by finger pressure, dries rapidly from a thin film on a finder to a powdery consistency. Laboratory: Has measureable Plastic and Liquid Limits and the Liquid Limit is 35% or less. Can be subdivided into low plasticity silt (Plasticity Index below A-Line on Casagrande Plot) and low plasticity clay (Plasticity Index above A-Line on Casagrande Plot).
Visual-Tactile: Behaves as a cohesive material, may or may not exhibit dilatancy, and feels smooth. Dried crumbs can be ruptured with moderate finger pressure, dries slowly from a thin film on a finger to a cake consistency. Laboratory: Has measureable Plastic and Liquid Limits and the Liquid Limit is greater than 35% but not greater than 50%. Can be subdivided into intermediate plasticity silt and clay based on position relative to A-Line on Casagrande Plot.
Visual-Tactile: Behaves as a cohesive material, will not readily exhibit dilatancy, and feels very smooth like butter or grease. Dried crumbs are difficult to rupture with strong finger pressure, dries very slowly and in a sticky manner from a thin film on a finger to a hard cake consistency. Laboratory: Has measureable Plastic and Liquid Limits and the Liquid Limit is greater than 50%. Can be subdivided into high plasticity silt and clay based on position relative to A-Line on Casagrande Plo .
Zone greater than 200 mm with numerous defects, and individual defects are difficult to delineate.
Core drilling but no core returned.
Individual defects can be identified and described.
No geotechnical information has been recorded for the unit.
Only chip returns. Only geotechnical information possibly available is weathering and estimated strength.
Unconsolidated material.
Core not containing any natural discontinuities.
| Code | Term | Description | Source |
|---|---|---|---|
| XA | Material is altered to such an extent that it has soil properties. Mass structure and material texture and fabric of original rock are still visible. Material is altered to such an extent that it has soil prope... | AS 1726 | |
| HA | The whole of the rock material is discoloured, usually by staining or bleaching to the extent that the colour of the original rock is not recognisable. Rock strength is changed by alteration. Some primary minerals are altered to clay minerals. Porosity may be increased by leaching, or may be decreased due to precipitation of secondary minerals in pores. The whole of the rock material is discoloured, usually by st... | AS 1726 | |
| MA | The whole of the rock material is discoloured, usually by staining or bleaching to the extent that the colour of the original rock is not recognisable but shows little or no change of strength from fresh rock. The whole of the rock material is discoloured, usually by st... | AS 1726 | |
| DA | The whole of the rock material is discoloured, usually by iron staining or bleaching to the extent that the colour of the original rock is not recognisable, but shows little or no change of strength from fresh rock. The whole of the rock material is discoloured, usually by ir... | AS 1726 | |
| SA | Where it is not practicable to distinguish between Highly Weathered and Moderately Weathered rock the term Distinctly Weathered may be used. Distinctly Weathered is defined as follows: Rock strength usually changed by weathering. The rock may be highly discoloured, usually by iron staining. Porosity may be increased by leaching, or may be decreased due to deposition of weathering products in pores. There is some change in rock strength. Where it is not practicable to distinguish between Highly We... | AS 1726 | |
| E | Rock is altered to such an extent that it has soil properties, i.e., it either disintegrates or can be remoulded, in water. Rock is altered to such an extent that it has soil propertie... | CoalLog | |
| D | Rock strength and mineralogy usually changed by alteration. The rock may be highly discoloured, usually by iron staining. Porosity may be increased by leaching, or may be decreased due to deposition of weathering products in pores. Rock strength and mineralogy usually changed by alteration. ... | CoalLog | |
| S | Rock is slightly discoloured but shows little or no change of strength from fresh rock. Usually penetrative alteration along defect surfaces. Rock is slightly discoloured but shows little or no change o... | CoalLog | |
| A | Degree of alteration not assessed. Degree of alteration not assessed. | CoalLog | |
| F | Rock shows no sign of decomposition or staining. Rock shows no sign of decomposition or staining. | CoalLog | |
| C1 | Exudes between the fingers when squeezed in hand [Undrained shear strength (su) <12 kPa]. Exudes between the fingers when squeezed in hand [Undrained ... | CoalLog | |
| C2 | Can be moulded by light finger pressure [Undrained shear strength (su) 12-25 kPa]. Can be moulded by light finger pressure [Undrained shear str... | CoalLog | |
| C3 | Can be moulded by strong finger pressure [Undrained shear strength (su) 25-50 kPa]. Can be moulded by strong finger pressure [Undrained shear st... | CoalLog | |
| C4 | Cannot be moulded by fingers, can be indented by thumb [Undrained shear strength (su) 50-100 kPa]. Cannot be moulded by fingers, can be indented by thumb [Undr... | CoalLog | |
| C5 | Can be indented by thumb nail [Undrained shear strength (su) 100-200 kPa]. Can be indented by thumb nail [Undrained shear strength (su)... | CoalLog | |
| C6 | Can be indented with difficulty by thumbnail [Undrained shear strength (su) >200 kPa]. Can be indented with difficulty by thumbnail [Undrained shea... | CoalLog | |
| S1 | Easily dissociated with flicks of finger nail [Relative density (Dr) <15%]. Easily dissociated with flicks of finger nail [Relative dens... | CoalLog | |
| S2 | Easily penetrated by knife blade, readily dissociated by scratching with finger nail [Relative density (Dr) 15-35%]. Easily penetrated by knife blade, readily dissociated by scr... | CoalLog | |
| S3 | Penetrated by knife only with firm pressure, readily indented by thumb pressure, dissociated with difficulty by scratching with finger nail [Relative density (Dr) 35-65%]. Penetrated by knife only with firm pressure, readily indente... | CoalLog | |
| S4 | Difficult to indent by thumb pressure, dissociated readily by knife blade [Relative density (Dr) 65-85%]. Difficult to indent by thumb pressure, dissociated readily b... | CoalLog | |
| S5 | Cannot be indented by thumb pressure; Dissociated only by firm pressure with knife blade [Relative density (Dr) >85%]. Cannot be indented by thumb pressure; Dissociated only by fi... | CoalLog | |
| R1 | May be broken by hand and remoulded (with the addition of water if necessary) to a material with soil properties [UCS <1 MPa]. May be broken by hand and remoulded (with the addition of wa... | CoalLog | |
| R2 | Crumbles under a single firm hammer blow; Can be peeled with a knife [UCS 1-5 MPa]. Crumbles under a single firm hammer blow; Can be peeled with... | CoalLog | |
| R3 | Breaks under a single firm hammer blow; Scored but not peeled with a knife [UCS 5-10 MPa]. Breaks under a single firm hammer blow; Scored but not peele... | CoalLog | |
| R4 | Breaks under 1 to 3 hammer blows; Can be scratched but not scored with a knife [UCS 10-25 MPa]. Breaks under 1 to 3 hammer blows; Can be scratched but not s... | CoalLog | |
| R5 | Breaks under 3 to 5 hammer blows; Hard to scratch with a knife; Can be scratched with tungsten-tipped tool; Hard sound when struck with hammer [UCS 25-50 MPa]. Breaks under 3 to 5 hammer blows; Hard to scratch with a kni... | CoalLog | |
| R6 | Breaks under 1 hammer blow if resting on solid surface; Cannot be scratched by knife; Scratched with difficulty by a tungsten-tipped tool; Dull ringing sound when struck with hammer [UCS 50-100 MPa]. Breaks under 1 hammer blow if resting on solid surface; Cann... | CoalLog | |
| R7 | Difficult to break with hammer even if resting on solid surface; Bright ringing sound when struck with hammer [UCS >100 MPa]. Difficult to break with hammer even if resting on solid surf... | CoalLog | |
| VS | Exudes between the fingers when squeezed in hand [Undrained shear strength (su) <12 kPa]. Exudes between the fingers when squeezed in hand [Undrained ... | AS 1726 | |
| S | Can be moulded by light finger pressure [Undrained shear strength (su) 12-25 kPa]. Can be moulded by light finger pressure [Undrained shear str... | AS 1726 | |
| F | Can be moulded by strong finger pressure [Undrained shear strength (su) 25-50 kPa]. Can be moulded by strong finger pressure [Undrained shear st... | AS 1726 | |
| St | Cannot be moulded by fingers [Undrained shear strength (su) 50-100 kPa]. Cannot be moulded by fingers [Undrained shear strength (su) ... | AS 1726 | |
| VSt | Can be indented by thumb nail [Undrained shear strength (su) 100-200 kPa]. Can be indented by thumb nail [Undrained shear strength (su)... | AS 1726 | |
| H | Can be indented with difficulty by thumb nail [Undrained shear strength (su) >200 kPa]. Can be indented with difficulty by thumb nail [Undrained she... | AS 1726 | |
| Fr | Can be easily crumbled or broken into small pieces by hand. Can be easily crumbled or broken into small pieces by hand. | AS 1726 | |
| VL | Relative density (Dr) <15%. Relative density (Dr) <15%. | AS 1726 | |
| L | Relative density (Dr) 15-35%. Relative density (Dr) 15-35%. | AS 1726 | |
| MD | Relative density (Dr) 35-65%. Relative density (Dr) 35-65%. | AS 1726 | |
| D | Relative density (Dr) 65-85%. Relative density (Dr) 65-85%. | AS 1726 | |
| VD | Relative density (Dr) >85%. Relative density (Dr) >85%. | AS 1726 | |
| VL | Material crumbles under firm blows with sharp end of pick; can be peeled with knife; too hard to cut a triaxial sample by hand. Pieces up to 30 mm thick can be broken by finger pressure [UCS 0.6-2 MPa; PLT Is(50) 0.03-0.1 MPa]. Material crumbles under firm blows with sharp end of pick; c... | AS 1726 | |
| L | UCS 2 - 6 MPa; Easily scored with a knife; indentations 1 mm to 3 mm show in the specimen with firm blows of the 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 [UCS 2-6 MPa; PLT Is(50) 0.1-0.3 MPa]. UCS 2 - 6 MPa; Easily scored with a knife; indentations 1 mm... | AS 1726 | |
| M | Readily scored with a knife; a piece of core 150 mm long by 50 mm diameter can be broken by hand with difficulty [UCS 6-20 MPa; PLT Is(50) 0.3-1 MPa]. Readily scored with a knife; a piece of core 150 mm long by ... | AS 1726 | |
| H | A piece of core 150 mm long by 50 mm diameter cannot be broken by hand but can be broken by a pick with a single firm blow; rock rings under hammer [UCS 20-60 MPa; PLT Is(50) 1-3 MPa]. A piece of core 150 mm long by 50 mm diameter cannot be brok... | AS 1726 | |
| VH | Hand specimen breaks with pick after more than one blow; rock rings under hammer [UCS 60-200 MPa; PLT Is(50) 3-10 MPa]. Hand specimen breaks with pick after more than one blow; roc... | AS 1726 | |
| EH | Specimen requires many blows with geological pick to break through intact material; rock rings under hammer [UCS >200 MPa; PLT Is(50) >10 MPa]. Specimen requires many blows with geological pick to break t... | AS 1726 | |
| RS | Material is weathered to such an extent that it has soil properties. Mass structure and material texture and fabric of original rock are no longer visible, but the soil has not been significantly transported. Material is weathered to such an extent that it has soil pro... | AS 1726 | |
| XW | Material is weathered to such an extent that it has soil properties. Mass structure and material texture and fabric of original rock are still visible. Material is weathered to such an extent that it has soil pro... | AS 1726 | |
| HW | The whole of the rock material is discoloured, usually by iron staining or bleaching to the extent that the colour of the original rock is not recognisable. Rock strength is significantly changed by weathering. Some primary minerals have weathered to clay minerals. Porosity may be increased by leaching, or may be decreased due to deposition of weathering products in pores. The whole of the rock material is discoloured, usually by ir... | AS 1726 | |
| MW | The whole of the rock material is discoloured, usually by iron staining or bleaching to the extent that the colour of the original rock is not recognisable, but shows little or no change of strength from fresh rock. The whole of the rock material is discoloured, usually by ir... | AS 1726 | |
| DW | Where it is not practicable to distinguish between Highly Weathered and Moderately Weathered rock the term Distinctly Weathered may be used. Distinctly Weathered is defined as follows: Rock strength usually changed by weathering. The rock may be highly discoloured, usually by iron staining. Porosity may be increased by leaching, or may be decreased due to deposition of weathering products in pores. There is some change in rock strength. Where it is not practicable to distinguish between Highly We... | AS 1726 | |
| SW | Rock is partially discoloured with staining or bleaching along joints but shows little or no change of strength from fresh rock. Rock is partially discoloured with staining or bleaching alo... | AS 1726 | |
| FR | Rock shows no sign of decomposition of individual minerals or colour changes. Rock shows no sign of decomposition of individual minerals o... | AS 1726 | |
| R | Soil developed on extremely weathered rock. The mass structure and substance fabric are no longer evident. There is a large change in volume but the soil has not been significantly transported Soil developed on extremely weathered rock. The mass structu... | CoalLog | |
| E | Rock is weathered to such an extent that it has soil properties, i.e., it either disintegrates or can be remoulded, in water. Rock is weathered to such an extent that it has soil propert... | CoalLog | |
| D | Rock strength usually changed by weathering. The rock may be highly discoloured, usually by iron staining. Porosity may be increased by leaching, or may be decreased due to deposition of weathering products in pores Rock strength usually changed by weathering. The rock may be... | CoalLog | |
| S | Rock is slightly discoloured but shows little or no change of strength from fresh rock. Usually penetrative weathering along defect surfaces Rock is slightly discoloured but shows little or no change o... | CoalLog | |
| F | Rock shows no sign of decomposition or staining Rock shows no sign of decomposition or staining | CoalLog | |
| K | No description available | CoalLog | |
| L | No description available | CoalLog | |
| B | No description available | CoalLog | |
| F | No description available | CoalLog | |
| C | No description available | CoalLog | |
| E | No description available | CoalLog | |
| G | No description available | CoalLog | |
| M | No description available | CoalLog | |
| X | No description available | CoalLog | |
| O | No description available | CoalLog | |
| P | No description available | CoalLog | |
| U | No description available | CoalLog | |
| R | No description available | CoalLog | |
| W | No description available | CoalLog | |
| Y | No description available | CoalLog | |
| C | TBC TBC | CoalLog | |
| D | TBC TBC | CoalLog | |
| V | TBC TBC | CoalLog | |
| T | TBC TBC | CoalLog | |
| AP | White to grey green globular masses or reniform at times with a subfibrous, scaly, or imperfectly columnar structure or as fibrous crusts. White to grey green globular masses or reniform at times wit... | CoalLog | |
| CA | Usually white but can also be colourless, grey, red, green, blue, yellow, brown, orange. White streak, vitreous lustre. Perfect rhombohedral cleavage. Low Mohs hardness (3). Dissolves in cold dilute HCl. Usually white but can also be colourless, grey, red, green, ... | CoalLog | |
| XR | Plant fragments that have undergone some form of coalification. Plant fragments that have undergone some form of coalificati... | CoalLog | |
| CB | White in colour. Soft and brittle. Fizzes violently with diluted HCl. White in colour. Soft and brittle. Fizzes violently with dil... | CoalLog | |
| CO | Varying shades of green, yellow, pink - usually lightly coloured. Vitreous to pearly lustre. Perfect basal cleavage. Relatively soft (2-2.5). Varying shades of green, yellow, pink - usually lightly colo... | CoalLog | |
| CL | Very fine grained sediment with platy minerals. Soft. Very fine grained sediment with platy minerals. Soft. | CoalLog | |
| CO | Carbon rich mineral deposit formed from the accumulation of organic matter and containing less than 50% ash yield on combustion; coal streaks brown (low rank) to black (high rank) when scratched with a metal tool. Carbon rich mineral deposit formed from the accumulation of ... | CoalLog | |
| CU | Breccia. Breccia. | CoalLog | |
| DI | White or slightly tinted. Transparent. Waxy feel with a satiny lustre. Soft (2-2.5). Perfect cleavage. White or slightly tinted. Transparent. Waxy feel with a sati... | CoalLog | |
| FO | Umbrella term for the preserved traces or remains of organisms from the remote geological past. Umbrella term for the preserved traces or remains of organis... | CoalLog | |
| GC | Dark-olive green. Platy-micaceous mineral. Very soft (2). Indicative of shallow marine/coastal shelf environment. Dark-olive green. Platy-micaceous mineral. Very soft (2). In... | CoalLog | |
| I | Can be applied to any natural defect except for Broken Zone (BZ) or Coal Cleat (CE). Does not contribute to Rock Quality Designation (RQD). Can be applied to any natural defect except for Broken Zone ... | CoalLog | |
| P | Smooth but without striations. Reflects light. Smooth but without striations. Reflects light. | CoalLog | |
| R | Rough to touch. Sandpaper feel. Rough to touch. Sandpaper feel. | CoalLog | |
| K | striations visible on defect surface that may or may not be polished (the angle of the striations to the dip direction of the defect should be noted). striations visible on defect surface that may or may not be ... | CoalLog | |
| S | Smooth to feel but not polished or slickensided. Smooth to feel but not polished or slickensided. | CoalLog | |
| C | One trough or crest across the core width. One trough or crest across the core width. | CoalLog | |
| I | Many sharp troughs and crests in all directions across the core width. Many sharp troughs and crests in all directions across the c... | CoalLog | |
| P | A surface with no obvious curves or irregularities across the core width. A surface with no obvious curves or irregularities across th... | CoalLog | |
| S | Distinct steps in any direction across the core width. Distinct steps in any direction across the core width. | CoalLog | |
| U | Rounded crests and troughs in one or more directions across the core width. Rounded crests and troughs in one or more directions across ... | CoalLog | |
| EW | Extremely wide defect spacing (<2 m). Extremely wide defect spacing (<2 m). | CoalLog | |
| VW | Very wide defect spacing (600-2000 mm). Very wide defect spacing (600-2000 mm). | CoalLog | |
| WI | Wide defect spacing (200-600 mm). Wide defect spacing (200-600 mm). | CoalLog | |
| MW | Moderately wide defect spacing (60-200 mm). Moderately wide defect spacing (60-200 mm). | CoalLog | |
| MN | Moderately narrow defect spacing (20-60 mm). Moderately narrow defect spacing (20-60 mm). | CoalLog | |
| NA | Narrow defect spacing (6-20 mm). Narrow defect spacing (6-20 mm). | CoalLog | |
| VN | Very narrow defect spacing (<6 mm). Very narrow defect spacing (<6 mm). | CoalLog | |
| BP | No description available | CoalLog | |
| BZ | No description available | CoalLog | |
| CL | No description available | CoalLog | |
| CE | No description available | CoalLog | |
| CF | No description available | CoalLog | |
| XB | No description available | CoalLog | |
| DY | No description available | CoalLog | |
| FT | No description available | CoalLog | |
| FO | No description available | CoalLog | |
| JT | No description available | CoalLog | |
| SH | No description available | CoalLog | |
| SI | No description available | CoalLog | |
| SO | No description available | CoalLog | |
| VN | No description available | CoalLog | |
| DS | No description available | CoalLog | |
| DB | No description available | CoalLog | |
| DZ | No description available | CoalLog | |
| K | No description available | CoalLog | |
| B | No description available | CoalLog | |
| B | No description available | CoalLog | |
| F | No description available | CoalLog | |
| C | No description available | CoalLog | |
| E | No description available | CoalLog | |
| G | No description available | CoalLog | |
| X | No description available | CoalLog | |
| O | No description available | CoalLog | |
| P | No description available | CoalLog | |
| U | No description available | CoalLog | |
| R | No description available | CoalLog | |
| W | No description available | CoalLog | |
| Y | No description available | CoalLog | |
| CU | Increase in grain size in sedimentary rock from base of the bed to its top. Termed reverse grading and is characteristic of some alluvial fan deposits. Increase in grain size in sedimentary rock from base of the ... | CoalLog | |
| FU | Decrease in grain size in sedimentary rock from base of the bed to its top. Termed normal grading and is characteristic of some turbidites and many sedimentary beds deposited in waning flow conditions. Decrease in grain size in sedimentary rock from base of the ... | CoalLog | |
| IL | Being positioned between or alternated with other laminations of dissimilar character where the layers are less then 20 mm thick. Being positioned between or alternated with other lamination... | CoalLog | |
| IB | Being positioned between or alternated with other layers of dissimilar character. Being positioned between or alternated with other layers of ... | CoalLog | |
| UB | TBC. TBC. | CoalLog | |
| UB | TBC. TBC. | CoalLog | |
| CB | Being positioned between or alternated with other layers of dissimilar character where the layers are >200 mm thick. Being positioned between or alternated with other layers of ... | CoalLog | |
| IR | TBC. TBC. | CoalLog | |
| IB | Existing or introduced between subordinate layers of a different type. It applies especially to layers of one kind of material that alternate with thicker strata of another material, e.g., Beds of shell intercalated with sandstone. Existing or introduced between subordinate layers of a diffe... | CoalLog | |
| IM | Existing with lithology(s) of a different type in no regular fashion and not forming regular structures. Existing with lithology(s) of a different type in no regular... | CoalLog | |
| DS | Widely dispersed throughout rock. Widely dispersed throughout rock. | CoalLog | |
| BN | TBC. TBC. | CoalLog | |
| BO | TBC. TBC. | CoalLog | |
| CM | TBC. TBC. | CoalLog | |
| CT | TBC. TBC. | CoalLog | |
| OO | TBC. TBC. | CoalLog | |
| FR | TBC. TBC. | CoalLog | |
| GG | TBC. TBC. | CoalLog | |
| LN | TBC. TBC. | CoalLog | |
| MX | TBC. TBC. | CoalLog | |
| ND | TBC. TBC. | CoalLog | |
| PB | TBC. TBC. | CoalLog | |
| PO | TBC. TBC. | CoalLog | |
| WP | TBC. TBC. | CoalLog | |
| N | Visual-Tactile: Behaves as a cohesionless material which may exhibit a dilatancy reaction when shaken but which cannot be moulded into a plastic solid including being rolled into a 3 mm diameter thread. Laboratory: Either or both the Plastic Limit and Liquid Limit cannot be determined by the test methods. Visual-Tactile: Behaves as a cohesionless material which may... | CoalLog | |
| B | Visual-Tactile: Behaves as a cohesive material but does not exhibit a dilatancy reaction and cannot be remoulded into a 3 mm thread. Laboratory: The Plastic Limit may or may not be measurable but the Liquid Limit cannot be measured by the test methods. Visual-Tactile: Behaves as a cohesive material but does not ... | CoalLog | |
| L | Visual-Tactile: Behaves as a cohesive material, may or may not exhibit dilatancy, and feels smooth but gritty. Dried crumbs are easily broken down by finger pressure, dries rapidly from a thin film on a finder to a powdery consistency. Laboratory: Has measureable Plastic and Liquid Limits and the Liquid Limit is 35% or less. Can be subdivided into low plasticity silt (Plasticity Index below A-Line on Casagrande Plot) and low plasticity clay (Plasticity Index above A-Line on Casagrande Plot). Visual-Tactile: Behaves as a cohesive material, may or may n... | CoalLog | |
| I | Visual-Tactile: Behaves as a cohesive material, may or may not exhibit dilatancy, and feels smooth. Dried crumbs can be ruptured with moderate finger pressure, dries slowly from a thin film on a finger to a cake consistency. Laboratory: Has measureable Plastic and Liquid Limits and the Liquid Limit is greater than 35% but not greater than 50%. Can be subdivided into intermediate plasticity silt and clay based on position relative to A-Line on Casagrande Plot. Visual-Tactile: Behaves as a cohesive material, may or may n... | CoalLog | |
| H | Visual-Tactile: Behaves as a cohesive material, will not readily exhibit dilatancy, and feels very smooth like butter or grease. Dried crumbs are difficult to rupture with strong finger pressure, dries very slowly and in a sticky manner from a thin film on a finger to a hard cake consistency. Laboratory: Has measureable Plastic and Liquid Limits and the Liquid Limit is greater than 50%. Can be subdivided into high plasticity silt and clay based on position relative to A-Line on Casagrande Plo . Visual-Tactile: Behaves as a cohesive material, will not rea... | CoalLog | |
| B | Zone greater than 200 mm with numerous defects, and individual defects are difficult to delineate. Zone greater than 200 mm with numerous defects, and individu... | CoalLog | |
| L | Core drilling but no core returned. Core drilling but no core returned. | CoalLog | |
| D | Individual defects can be identified and described. Individual defects can be identified and described. | CoalLog | |
| N | No geotechnical information has been recorded for the unit. No geotechnical information has been recorded for the unit. | CoalLog | |
| O | Only chip returns. Only geotechnical information possibly available is weathering and estimated strength. Only chip returns. Only geotechnical information possibly av... | CoalLog | |
| S | Unconsolidated material. Unconsolidated material. | CoalLog | |
| U | Core not containing any natural discontinuities. Core not containing any natural discontinuities. | CoalLog | |
| L | No description available | CoalLog | |
| A | No description available | CoalLog | |
| C | No description available | CoalLog | |
| E | No description available | CoalLog | |
| B | No description available | CoalLog | |
| D | No description available | CoalLog | |
| N | No description available | CoalLog | |
| M | No description available | CoalLog | |
| S | No description available | CoalLog | |
| V | No description available | CoalLog | |
| QP | No description available | CoalLog | |
| QB | No description available | CoalLog | |
| QU | No description available | CoalLog | |
| LP | No description available | CoalLog | |
| SP | No description available | CoalLog | |
| SB | No description available | CoalLog | |
| SU | No description available | CoalLog | |
| GT | No description available | CoalLog | |
| GF | No description available | CoalLog | |
| WT | No description available | CoalLog | |
| WF | No description available | CoalLog | |
| ME | No description available | CoalLog | |
| MD | No description available | CoalLog | |
| ES | No description available | CoalLog | |
| EO | No description available | CoalLog | |
| ER | No description available | CoalLog | |
| AD | No description available | CoalLog | |
| PN | No description available | CoalLog | |
| PE | No description available | CoalLog |
A geotechnical dictionary is a comprehensive reference tool that provides standardised classifications, definitions, and terminology used in geotechnical engineering and geology. This resource consolidates various classification systems for rock strength, material weathering, soil properties, colour classifications, defect characteristics, plasticity, and other geological characteristics that are essential for engineering design, construction planning, and geological interpretation.
This dictionary includes classifications from recognised Australian and international standards:
Geotechnical site investigations
Coal industry specific classifications
The geotechnical dictionary provides several ways to access and search classification data:
Use the search bar to find specific terms, codes, or descriptions across all classification categories.
Browse different classification categories including rock strength, weathering, soil properties, colour classifications, defect characteristics, plasticity, and more.
Each classification includes detailed descriptions, codes, and applicable standards.
Where applicable, view numerical ranges for strength values and test parameters.
This geotechnical dictionary is valuable for:
The classifications in this dictionary are based on established standards and guidelines:
The CMRR calculator aids in the evaluation of underground coal mine roof stability by providing a rating that combines rock core logging with visual assessment.
Calculate the rock mass quality using the Q-system, helping engineers determine ground support requirements and predict stability in tunneling, underground mine roadways, and ventilation shafts.
Visualise and analyse borehole wireline geophysical log data from LAS files with this interactive tool.
Calculate the gauge pressure for each stage of a water pressure (packer) test, helping engineers determine the appropriate pressure for each stage.
Comprehensive searchable database of engineering standards including Australian Standards (AS), ISO, and ASTM for geotechnical engineering, soil testing, rock mechanics, and foundation design.
Visualise and design stable mine slopes with interactive geometry tools. Optimise bench height, batter angles, and overall slope configurations for open pit mining operations.
Quickly and easily calculate the geometry for a mining-compliant safety bund.
Estimate the uniaxial compressive strength (UCS) of rock materials through non-destructive sonic testing, providing crucial data for geotechnical engineering.
Convert point load strength index values to UCS for rocks using empirical correlations, facilitating quicker field assessments without extensive laboratory testing.