Mohs Scale of Mineral Hardness
The Mohs scale of hardness is a system used to classify minerals based on their scratch resistance. It was developed by Friedrich Mohs in 1812 and is still widely used today by geologists, mineralogists, and other scientists to identify and compare the relative hardness of different minerals.
The Mohs scale ranks minerals from 1 to 10, with 1 being the softest and 10 being the hardest. The scale is based on the ability of one mineral to scratch another mineral, so a mineral with a higher number can scratch a mineral with a lower number, but not the other way around.
Here are the minerals and their corresponding ranking on the Mohs scale:
- Talc
- Gypsum
- Calcite
- Fluorite
- Apatite
- Orthoclase feldspar
- Quartz
- Topaz
- Corundum
- Diamond
For example, a mineral with a hardness of 7 can scratch all minerals with a hardness of less than 7, but cannot scratch minerals with a hardness greater than 7. Therefore, quartz, with a hardness of 7, is harder than feldspar, with a hardness of 6.
The Mohs scale is a useful tool for mineral identification and classification because it is simple, quick, and non-destructive. However, it should be noted that it does not accurately reflect the absolute hardness of minerals, as the scale only measures relative scratch resistance.
Comprehensive Mohs Scale Mineral List
The below table is a comprehensive list of minerals and their Mohs ranking.
Diamond
10
Corundum
9
Ruby
9
Sapphire
9
Alexandrite
8.5
Chrysoberyl
8.5
Rhodozite
8
Spinel
8
Taaffeite
8
Topaz
8
Yag
8
Aquamarine
7.5 – 8
Beryl
7.5 – 8
Emerald
7.5 – 8
Gahnite
7.5 – 8
Painite
7.5 – 8
Phenacite
7.5 – 8
Almandine
7.5
Andalusite
7.5
Euclase
7.5
Hambergite
7.5
Uvarovite
7.5
Ceramic Streak Plate
7.5
Andradite
7 – 7.5
Cordierite
7 – 7.5
Danburite
7 – 7.5
Garnet
7 – 7.5
Iolite
7 – 7.5
Rhodolite
7 – 7.5
Staurolite
7 – 7.5
Tourmaline
7 – 7.5
Amethyst
7
Citrine
7
Dumortierite
7
Prasiolite
7
Rock-Crystal
7
Quartz (Smoky, Rose)
7
Tigers Eye
7
Zircon
6.5 – 7.5
Agate
6.5 – 7
Axinite
6.5 – 7
Chalcedony
6.5 – 7
Chloromelanite
6.5 – 7
Chrysoprase
6.5 – 7
Demantoid
6.5 – 7
Petrified Wood
6.5 – 7
Heliotrope
6.5 – 7
Jadeite
6.5 – 7
Jasper
6.5 – 7
Kornerupine
6.5 – 7
Peridot
6.5 – 7
Sard
6.5 – 7
Tanzanite
6.5 – 7
Ziosite
6.5 – 7
Idocrase
6.5
Saussurite
6.5
Sinhalite
6.5
Smaragdite
6.5
Steel File
6.5
Sillimanite
6 – 7.5
Epidote
6 – 7
Cassiterite
6 – 7
Epidote
6 – 7
Hiddenite
6 – 7
Kunzite
6 – 7
Unakite
6 – 7
Amazonite
6 – 6.5
Aventurine
6 – 6.5
Feldspar
6 – 6.5
Benitoite
6 – 6.5
Ekanite
6 – 6.5
Labradorite
6 – 6.5
Moonstone
6 – 6.5
Nephrite-Jade
6 – 6.5
Petalite
6 – 6.5
Prehnite
6 – 6.5
Pyrite
6 – 6.5
Rutile
6 – 6.5
Strontium
6 – 6.5
Titanate
6 – 6.5
Amblygonite
6
Bytownite
6
Orthoclase
6
Sanidine
6
Thulite
6
Tugtupite
6
Hematite
5.5 – 6.5
Opal
5.5 – 6.5
Rhodonite
5.5 – 6.5
Tremolite
5.5 – 6.5
Actinolite
5.5 – 6.5
Anatase
5.5 – 6.5
Beryllonite
5.5 – 6
Elaeolite
5.5 – 6
Hauynite
5.5 – 6
Periclase
5.5 – 6
Psilomelane
5.5 – 6
Sodalite
5.5 – 6
Brazilianite
5.5
Chromite
5.5
Enstatite
5.5
Goldstone
5.5
Leucite
5.5
Moldavite
5.5
Natrolite
5.5
Willemite
5.5
Window Glass
5.5
Scapolite
5 – 6.5
Cancrinite
5 – 6
Chlorastrolite
5 – 6
Diopside
5 – 6
Hypersthene
5 – 6
Limenite
5 – 6
Lapis Lazuli
5 – 6
Lazulite
5 – 6
Tantalite
5 – 6
Turquoise
5 – 6
Datolite
5 – 5.5
Obsidian
5 – 5.5
Sphene
5 – 5.5
Thomasonite
5 – 5.5
Steel Knife Blade
5.5
Apatite
5
Augelite
5
Dioptase
5
Hemimorphite
5
Smithsonite
5
Wardite
5
Kyanite
4.5 – 7
Apophyllite
4.5 – 5
Scheelite
4.5 – 5
Zincite
4.5 – 5
Colemanite
4.5
Kurnakovite
4.5
Purpurite
4.5
Wire Nail
4.5
Variscite
4.5
Flourite
4
Barytocalcite
4
Magnesite
4
Rhodochrosite
4
Dolomite
3.5 – 4.5
Chalybite
3.5 – 4.5