Mohs Hardness Scale Reference

The Mohs hardness scale ranks minerals by scratch resistance from 1 (talc, softest) to 10 (diamond, hardest). It is an ordinal scale: each step can scratch everything below it. Geologists and collectors use Mohs to identify minerals in the field with simple tools like a steel file or glass plate.

This page is a reference chart, not a converter between Mohs and metal test scales. Rockwell C, Brinell, Vickers, and Shore hardness use different indenters and loads; their numbers correlate only approximately for specific alloys and heat treatments. Drawings and mill certificates specify a test method — do not substitute converted values for required QA tests.

Knife enthusiasts quote HRC edge retention while phone cases list Shore A flexibility; both measure deformation resistance but with incompatible methods. When a supplier lists Brinell and your spec lists Rockwell, use the manufacturer's conversion table for that material grade rather than a generic chart.

Heat treat shops verify quench success against HRC targets on tool steel. Case depth and surface treatments skew readings if the indenter reaches unaffected core material. Metallurgy students learn that hardness conversion is indicative only for safety-critical parts.

Use this Mohs reference when learning mineral identification, comparing scratch resistance in geology coursework, or explaining why quartz (Mohs 7) scratches glass (~5.5) but not topaz (Mohs 8).