Scratch Hardness of Rock(Mohs Scale · ISRM Practice)
Scratch hardness classification of rock and mineral specimens on the Mohs scale following ISRM-aligned practice — a rapid mineralogical and abrasivity indicator for excavation, drilling and dimension-stone decisions.
What is the Scratch Hardness Test of Rock?
Scratch hardness places a rock's constituent minerals on the Mohs scale (1–10) by testing which reference minerals scratch it and which it scratches. Simple as it is, the result carries real engineering weight: it signals abrasivity — how fast a rock will wear TBM cutters, drill bits and crusher liners — and supports mineral identification, weathering assessment and dimension-stone finishing decisions. There is no dedicated IS code for rock scratch hardness; Indian labs follow Mohs-scale practice consistent with ISRM characterisation guidance, which is how Global Lab performs and reports it.
Testing uses a calibrated Mohs reference set on fresh rock surfaces, classifying each significant mineral phase and assigning a representative hardness range for the rock, with abrasivity commentary where excavation planning is the purpose.
How the Scratch Hardness of Rock is Conducted
- 1
Surface Preparation
A fresh, unweathered surface is exposed and cleaned; weathered rinds are noted separately. - 2
Reference Scratching
Reference minerals are applied in sequence to bracket each phase between the hardest mineral that fails to scratch it and the softest that does. - 3
Phase Classification
Each significant mineral phase is assigned its Mohs bracket; the dominant-phase hardness defines the rock's representative value. - 4
Abrasivity Interpretation
Where requested, hardness results are interpreted for excavation and wear implications. - 5
Reporting
Phase-wise hardness, representative range and commentary are issued via Autovity QLMS.
Applicable Test Standards
| Standard | Title | Scope | Type |
|---|---|---|---|
| Mohs Scale | Mohs Scale of Mineral Hardness (Reference Minerals 1–10) | Classification Basis | Reference |
| ISRM SM | ISRM Suggested Methods for Rock Characterization | Characterisation Practice | International |