The Measurement of Hardness Scale is a useful tool in quickly determining the hardness of minerals in the field. It also provides insight into the durability of the stones that we work with. The hardness of the stone informs whether it will be suitable to create curved, cantilever or spiral staircases. Our own infographic shows where these stones fall in comparison to the other natural materials on the scale:
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The Mohs Scale of Mineral Hardness
In 1822 German mineralogist Friedrich Mohs created his Mohs Hardness Scale to measure the hardness of various minerals. At the time, Mohs based it on minerals that were readily available to him by taking a mineral and finding the hardest other material that it could scratch. The result is this ordinal scale of minerals by hardness, with 1 being the softest and 10 being the hardest.
To give you an idea of how durable the stones in our staircases and fireplaces are, we have added them to our revised version of the hardness scale:
The Mohs Scale of Mineral Hardness
1. Talc
2. Gypsum
3. Calcite
3.5 Limestone
Some of the limestones that we work with are Ancaster, Bath, Moleanos and Portland. To scratch these you would have to strike them with a knife or harder mineral.
4. Marble
Some of the marbles that we use are Carrara, Boticcino, Thassos and Calacatta.
5. Apatite
6. Orthoclase
6.5 Granite
Granites, like the Black Granite that we work with, rate between 6 and 7 on the Mohs scale. A knife will do virtually nothing to a stone this hard, while the mineral itself can scratch glass and weaker stones and only be scatched itself by something harder.
7. Quartz
8. Topaz
9. Corundum
10. Diamond
Even today, the Mohs Hardness Scale is used by field geologists and other professionals to make quick, rough identifications of new materials. Mohs’ surname also lends itself to the excellent backronym of ‘Measurement Of Hardness Scale’. When it comes to our own stonemasonry projects, each of them comes with a comprehensive aftercare package with everything you need to enhance, protect and ensure a long life for your stoneware.
Ian Knapper has over 25 years’ experience as a mason with works across heritage, private and public sectors. Get in touch and find out what we can do for you and your next stonework project.
Ian Knapper designs and creates beautiful things in natural stone. Follow us on Twitter @Ian_Knapper or search for us on Facebook.
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