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Grade 3 Science · World 1: Rock Hounds · Level 5
The Mohs Scale
Order minerals from 1 (talc) to 10 (diamond), and know that a harder mineral scratches a softer one.
Warm-up, learn, try it together, practice, then a quick check. About 15 minutes.
What children learn in Level 5
- Long ago, a scientist named Friedrich Mohs made a scale to rank minerals by hardness, from 1 to 10.
- Talc, number 1, is so soft you can scratch it with your fingernail. Diamond, number 10, is the hardest mineral on the scale.
- A mineral can scratch any mineral below it on the scale. Quartz, 7, scratches feldspar, 6. But feldspar can't scratch quartz.
- The testers fit on the scale too. Glass is about 5½, so only minerals 6 and up can scratch it.
Georgia Standards of Excellence in Science:
- S3E1.a — Ask questions and analyze data to classify rocks by their physical attributes (color, texture, luster, and hardness) using simple tests. (Clarification statement: Mohs scale should be studied at this level. Cleavage, streak and the classification of rocks as sedimentary, igneous, and metamorphic are studied in sixth grade.)