Mohs hardness orders minerals by resistance to scratching. Talc has hardness one, calcite three and quartz seven. A harder reference can scratch a softer specimen. The activity shows virtual tests with known references. It illustrates comparisons, not a complete method for identifying every possible natural sample.
Earth and geology · Discover & try
How can tests distinguish minerals?
Reading level 2 of 5 · DevelopingChange
Word help
Hardness
Relative resistance to scratching.
Streak
The colour of a mineral’s powder on a streak plate.
Lustre
How a mineral surface reflects light.
Watch · Try · Explain
See how it works
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Virtual tests and reference properties; original crystal drawings are not measured specimens or a complete identification key.
What to look for
- Use a harder and a softer reference.
- Compare the remaining candidate set.
- Do not treat the Mohs scale as a linear ratio.
Explain what you noticed
An unfamiliar specimen scratches calcite (3) but is scratched by orthoclase (6). What is supported?
Keep this idea: Several properties are more useful than colour alone, and hardness describes scratching resistance.
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Source material checked 2026-10-28. Explanations and activities by Nepedia. Source links do not imply endorsement.
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