When it comes to measuring the hardness of minerals, the Mohs scale is an effective method. This scale was established in 1824 by a German mineralogist and geologist, Friedrich Mohs, and since then, has been used as a reliable measure for identifying mineral hardness.
The Mohs scale consists of 10 hardiness points ranked in order from softest at 1 being talc to diamond being hardest at 10.
Each number on the scale can be compared with another to determine which is harder or softer than the other. For example, diamond is much harder than quartz; therefore, diamond is ranked higher than quartz on the Mohs scale.
Table of Contents
History of the Mohs Scale
It has long been customary for mineralogists to identify or assess the properties of stones or minerals by some type of scratch hardness test. The test, which has been most firmly established for more than a century, is due to Mohs (1824), who proposed ten minerals in increasing order of scratch hardness.
Each mineral will scratch the one on the scale below it but will not scratch the one above it. At first sight, it would appear that such a scale might be so arbitrary as to have no basic physical significance.
Interestingly, Mohs himself was aware of this difficulty, and in selecting his standard minerals for the construction of his scratch hardness scale, he emphasizes that “the intervals between every two members of the scale be not so disproportionate as either to render its employment more difficult or to hinder it all together.”
Consequently, with these precautions in mind, he finally proposed his ten basic minerals :
1. talc 2. gypsum, 3. calcite, 4. fluorite, 5. apatite, 6. orthoclase, 7. quartz, 8. topaz, 9. corundum and 10. diamond.
Even so Mohs was conscious of the fact that the intervals were not everywhere of the same magnitude, and he points out that the gap between corundum and diamond and, to a lesser extent, between apatite and orthoclase is greater than it should be.
Nevertheless, as he concludes in his introductory remarks, “it is very difficult to ascertain the perfect equality of the intervals between the different degrees of hardness, and on that account also it is very difficult to be obtained.
By using this scale, it is possible to determine the relative hardness between different minerals. Additionally, it can be used to help identify unknown minerals. Mohs’ legacy has endured thanks to his contributions to mineralogy; he created a system still in use today.
His work has been integral to the identification of minerals and rocks, helping to classify them and build an understanding of their relative hardness. Mohs is considered one of the most important contributors to mineralogy in modern times.
The Modern Mohs Scale
| Name | Hardness |
|---|---|
| Diamond | 10 |
| Synth. Moissanit | 9½ |
| Ruby | 9 |
| Sapphire | 9 |
| Alexandrite | 8.5 |
| Chrysoberyll | 8.5 |
| Holtite | 8.5 |
| YAG | 8.5 |
| Zirconia | 8.5 |
| Rhodizite | 8 - 8.5 |
| Taafeite | 8 - 8.5 |
| Spinel | 8 |
| Topaz | 8 |
| Aquamarine | 7.5 - 8 |
| Red Beryl | 7.5 - 8 |
| Precious Beryl | 7.5 - 8 |
| Gahnite | 7.5 - 8 |
| Galaxite | 7.5 - 8 |
| Painite | 7.5 - 8 |
| Phenakite | 7.5 - 8 |
| Emerald | 7.5 - 8 |
| Andalusite | 7.5 |
| Euclase | 7.5 |
| Hambergite | 7.5 |
| Sapphirine | 7.5 |
| Dumortierite | 7 - 8.5 |
| Almandine | 7 - 7.5 |
| Boracite | 7 - 7.5 |
| Cordierite | 7 - 7.5 |
| Danburite | 7 - 7.5 |
| Grandidierite | 7 - 7.5 |
| Pyrope | 7 - 7.5 |
| Schorlomite | 7 - 7.5 |
| Sekaninaite | 7 - 7.5 |
| Simpsonite | 7 - 7.5 |
| Spessartine | 7 - 7.5 |
| Staurolite | 7 - 7.5 |
| Turmaline | 7 - 7.5 |
| Uvarovite | 7 - 7.5 |
| Amethyst | 7 |
| Aventurine | 7 |
| Rock Crystal | 7 |
| Chambersite | 7 |
| Chromdravite | 7 |
| Citrine | 7 |
| Forsterite | 7 |
| Povondraite | 7 |
| Quartz | 7 |
| Smoky Quartz | 7 |
| Zunyite | 7 |
| Garnet | 6.5 - 7.5 |
| Jeremejevite | 6.5 - 7.5 |
| Sillimanite | 6.5 - 7.5 |
| Zircon | 6.5 - 7.5 |
| Axinite | 6.5 - 7 |
| Chalcedony | 6.5 - 7 |
| Chrysoprase | 6.5 - 7 |
| Diaspore | 6.5 - 7 |
| Ferro-Axinite | 6.5 - 7 |
| Gadolinite | 6.5 - 7 |
| Grossular | 6.5 - 7 |
| Hiddenite | 6.5 - 7 |
| Jadeite | 6.5 - 7 |
| Jasper | 6.5 - 7 |
| Kornerupine | 6.5 - 7 |
| Kunzite | 6.5 - 7 |
| Mangan-Axinite | 6.5 - 7 |
| Peridot | 6.5 - 7 |
| Pollucite | 6.5 - 7 |
| Serendibite | 6.5 - 7 |
| Sinhalite | 6.5 - 7 |
| Spodumene | 6.5 - 7 |
| Tanzanite | 6.5 - 7 |
| Thorianite | 6.5 - 7 |
| Tinzenite | 6.5 - 7 |
| Gadolinium gallium garnet | 6.5 |
| Magnesio-Axinite | 6.5 |
| Nambulite | 6.5 |
| Vesuvianite | 6.5 |
| Cassiterite | 6-7 |
| Clinozoisite | 6-7 |
| Epidote | 6-7 |
| Hancockite | 6-7 |
| Pyrolusite | 6-7 |
| Sogdianite | 6-7 |
| Amazonite | 6 - 6.5 |
| Andesine | 6 - 6.5 |
| Anorthoclase | 6 - 6.5 |
| Benitoite | 6 - 6.5 |
| Bixbyite | 6 - 6.5 |
| Bytownite | 6 - 6.5 |
| Chondroite | 6 - 6.5 |
| Helvite | 6 - 6.5 |
| Hyalophane | 6 - 6.5 |
| Labradorite | 6 - 6.5 |
| Marcasite | 6 - 6.5 |
| Microcline | 6 - 6.5 |
| Nephrite | 6 - 6.5 |
| Norbergite | 6 - 6.5 |
| Oligoclase | 6 - 6.5 |
| Petalite | 6 - 6.5 |
| Prehnite | 6 - 6.5 |
| Pyrite | 6 - 6.5 |
| Rutile | 6 - 6.5 |
| Sanidine | 6 - 6.5 |
| Smaragdite | 6 - 6.5 |
| Sugilite | 6 - 6.5 |
| Tantalite | 6 - 6.5 |
| Xonotlite | 6 - 6.5 |
| Zoisite | 6 - 6.5 |
| Aegirine | 6 |
| Amblygonite | 6 |
| Clinohumite | 6 |
| Humite | 6 |
| Hurlbutite | 6 |
| Lawsonite | 6 |
| Pumpellyite | 6 |
| Tephroite | 6 |
| Vlasovite | 6 |
| Zektzerite | 6 |
| Hematite | 5.5 - 6.5 |
| Hedenbergite | 5.5 - 6.5 |
| Magnetite | 5.5 - 6.5 |
| Manganotantalite | 5.5 - 6.5 |
| Opal | 5.5 - 6.5 |
| Rhodonite | 5.5 - 6.5 |
| Actinolite | 5.5 - 6 |
| Allanite | 5.5 - 6 |
| Anatase | 5.5 - 6 |
| Beryllonite | 5.5 - 6 |
| Brookite | 5.5 - 6 |
| Bustamite | 5.5 - 6 |
| Canasite | 5.5 - 6 |
| Cobaltite | 5.5 - 6 |
| Euxenite | 5.5 - 6 |
| Fabulite | 5.5 - 6 |
| Fergusonite | 5.5 - 6 |
| Haüyne | 5.5 - 6 |
| Leucite | 5.5 - 6 |
| Marialite | 5.5 - 6 |
| Meionite | 5.5 - 6 |
| Milarite | 5.5 - 6 |
| Montebrasite | 5.5 - 6 |
| Natromontebrasite | 5.5 - 6 |
| Periclase | 5.5 - 6 |
| Pyroxmangite | 5.5 - 6 |
| Sarcolite | 5.5 - 6 |
| Scorzalite | 5.5 - 6 |
| Scapolite | 5.5 - 6 |
| Sodalite | 5.5 - 6 |
| Tugtupite | 5.5 - 6 |
| Brazilianite | 5.5 |
| Breithauptite | 5.5 |
| Chromite | 5.5 |
| Enstatite | 5.5 |
| Linobate | 5.5 |
| Magnesiochromite | 5.5 |
| Moldavite | 5.5 |
| Willemite | 5.5 |
| Analcime | 5 - 5.5 |
| Datolite | 5 - 5.5 |
| Durangite | 5 - 5.5 |
| Eudialyte | 5 - 5.5 |
| Goethite | 5 - 5.5 |
| Herderite | 5 - 5.5 |
| Hydroxylherderite | 5 - 5.5 |
| Meliphanite | 5 - 5.5 |
| Mesolite | 5 - 5.5 |
| Microlite | 5 - 5.5 |
| Monazite | 5 - 5.5 |
| Natrolite | 5 - 5.5 |
| Nickeline | 5 - 5.5 |
| Papagoite | 5 - 5.5 |
| Psilomelane | 5 - 5.5 |
| Scolecite | 5 - 5.5 |
| Sellaite | 5 - 5.5 |
| Thomsonite | 5 - 5.5 |
| Titanite | 5 - 5.5 |
| Wolframite | 5 - 5.5 |
| Yttrotantalite | 5 - 5.5 |
| Apatite | 5 |
| Bismutotantalite | 5 |
| Childrenite | 5 |
| Chlorapatite | 5 |
| Dioptase | 5 |
| Eosphorite | 5 |
| Flourapatite | 5 |
| Hemimorphite | 5 |
| Hydroxylapatite | 5 |
| Mangan-Apatite | 5 |
| Odontolite | 5 |
| Rinkite | 5 |
| Schlossmacherite | 5 |
| Smithsonite | 5 |
| Spurrite | 5 |
| Strass | 5 |
| Vayrynenite | 5 |
| Ekanite | 4.5 - 6.5 |
| Apophyllite | 4.5 - 5 |
| Augelite | 4.5 - 5 |
| Charoite | 4.5 - 5 |
| Gaspéite | 4.5 - 5 |
| Hodgkinsonite | 4.5 - 5 |
| Legrandite | 4.5 - 5 |
| Pectolite | 4.5 - 5 |
| Scheelite | 4.5 - 5 |
| Wardite | 4.5 - 5 |
| Wollastonite | 4.5 - 5 |
| Bayldonite | 4.5 |
| Colemanite | 4.5 |
| Parisite | 4.5 |
| Prosopite | 4.5 |
| Yugawaralite | 4.5 |
| Sérandite | 4 - 5.5 |
| Carletonite | 4 - 4.5 |
| Hübnerite | 4 - 4.5 |
| Purpurite | 4 - 4.5 |
| Algodonite | 4 |
| Ammonite | 4 |
| Barytocalcite | 4 |
| Flourite | 4 |
| Leucophanite | 4 |
| Libethenite | 4 |
| Rhodochrosite | 4 |
| Magnesite | 3.5 - 4.5 |
| Siderite | 3.5 - 4.5 |
| Ankerite | 3.5 - 4 |
| Aragonite | 3.5 - 4 |
| Azurite | 3.5 - 4 |
| Chalcopyrite | 3.5 - 4 |
| Creedite | 3.5 - 4 |
| Cuprite | 3.5 - 4 |
| Dickinsonite | 3.5 - 4 |
| Dolomite | 3.5 - 4 |
| Euchroite | 3.5 - 4 |
| Langbeinite | 3.5 - 4 |
| Malachite | 3.5 - 4 |
| Mimetite | 3.5 - 4 |
| Pentlandite | 3.5 - 4 |
| Powellite | 3.5 - 4 |
| Scorodite | 3.5 - 4 |
| Shungite | 3.5 - 4 |
| Shattuckite | 3.5 - 4 |
| Sphalerite | 3.5 - 4 |
| Wavellite | 3.5 - 4 |
| Wurtzite | 3.5 - 4 |
| Adamite | 3.5 |
| Anhydrite | 3.5 |
| Chiolite | 3.5 |
| Huréaulite | 3.5 |
| Strontianite | 3.5 |
| Thaumasite | 3.5 |
| Weloganite | 3.5 |
| Anglesite | 3 - 3.5 |
| Baryte | 3 - 3.5 |
| Boleite | 3 - 3.5 |
| Cerussite | 3 - 3.5 |
| Celestine | 3 - 3.5 |
| Descloizite | 3 - 3.5 |
| Greenockite | 3 - 3.5 |
| Howlite | 3 - 3.5 |
| Millerite | 3 - 3.5 |
| Phosphophyllite | 3 - 3.5 |
| Witherite | 3 - 3.5 |
| Bornite | 3 |
| Calcite (Pearl) | 3 |
| Kurnakovite | 3 |
| Shortite | 3 |
| Wulfenite | 3 |
| Serpentine | 2.5 - 5.5 |
| Pearl | 2.5 - 4.5 |
| Jet | 2.5 - 4 |
| Chalcocite | 2.5 - 3 |
| Crocoite | 2.5 - 3 |
| Gaylussite | 2.5 - 3 |
| Gold | 2.5 - 3 |
| Inderite | 2.5 - 3 |
| Lepidolite | 2.5 - 3 |
| Pyrargyrite | 2.5 - 3 |
| Silver | 2.5 - 3 |
| Stolzite | 2.5 - 3 |
| Vanadinite | 2.5 - 3 |
| Whewellite | 2.5 - 3 |
| Brucite | 2.5 |
| Cryolite | 2.5 |
| Linarite | 2.5 |
| Lizardite | 2.5 |
| Proustite | 2.5 |
| Sturmanite | 2.5 |
| Amber | 2 - 2.5 |
| Cinnabar | 2 - 2.5 |
| Ettringite | 2 - 2.5 |
| Kämmererite | 2 - 2.5 |
| Mellite | 2 - 2.5 |
| Senarmontite | 2 - 2.5 |
| Ulexite | 2 - 2.5 |
| Villiaumite | 2 - 2.5 |
| Gypsum | 2 |
| Stichtite | 1.5 - 2.5 |
| Sulphur | 1.5 - 2.5 |
| Covellite | 1.5 - 2 |
| Melonite | 1.5 - 2 |
| Realgar | 1.5 - 2 |
| Vivianite | 1.5 - 2 |
| Talc | 1 |
Mixing Pearls with other Jewelry pieces
When it comes to selecting pearls for jewelry pieces, understanding what materials are used for gemstone identification is invaluable. Knowing the hardness of your gemstones can help you determine if they are suitable for a particular type of jewelry or setting.
The Mohs scale can help you understand what kind of materials your pearls should be set with and even how to clean them correctly. Pearls are delicate, ranging from 2.5-3.5 on the Mohs scale, so only certain metals should be used when creating jewelry pieces featuring these gems.
Gold, silver, and platinum are all popular choices because they can protect the pearls from damage. Additionally, special care should be taken when cleaning your pearl jewelry so as not to dull its sparkle and shine.
By taking into consideration the Mohs scale information, you can ensure that your pearls will remain as beautiful as they were when you first acquired them!
Takeaway
No matter what type of gemstone you are dealing with, it’s important to understand its hardness before attempting to set or clean it. The Mohs scale is a useful tool for jewelers and hobbyists alike; it gives us an idea of which materials are suitable for adorning our precious gems and how we can best preserve their beauty.
For those who appreciate the exquisite elegance of pearls, understanding the Mohs scale can help to ensure that these gems sparkle and shine for generations to come.
When it comes to selecting the perfect pearls, whether they be for a ring, pendant or bracelet, taking into account the hardness rating of your gemstone is essential.
With the knowledge of Friedrich Mohs’ scale, you can confidently make an informed decision on what type of setting and care best suits your pearl jewelry. Knowing how to correctly preserve the beauty and integrity of your pearls will guarantee that you can enjoy their timeless elegance forever!
References
D Tabor. Mohs’s Hardness Scale – A Physical Interpretation. 1954 Proc. Phys. Soc. B 67 249
