news material We’ve found a new mineral that’s even harder than diamond (and it’s from space!)
55 years after its initial discovery in Arizona, Lonsdaleite, named after the famous chemist Kathleen Lonsdale, is finally recognized as a mineral in its own right and its properties are breathtaking!
Understanding the Strength and Hardness of Minerals with the Mohs Scale
Before returning to this incredible discovery and to understand what its real impact is, it is important to talk about the Mohs scale and explain what it consists of.
The Mohs scale was devised in 1812 by the German mineralogist Friedrich Mohs (hence the name…) in order to measure the hardness of minerals. Historically, it was based on ten fairly common minerals, ranked from softest to hardest.
The principle of this scale is to oppose minerals to each other and their ability to scratch against each other. Thus, since this scale exists, the diamond is the reference in the matter with a score of 10 out of 10. That is, it can only be scratched by another diamond.
Below, at 9 out of 10, we find Ruby and Sapphire, grouped together in the “Corundum” family, which we know well since this is what equips the screens of hiking and high mountain watches in particular. Sapphire has the particularity of being available in large quantities, not too expensive and easy to work with. Then come Topaz (8/10), Quartz (7/10) and so on…
Subsequently, as discoveries and uses progressed, the Mohs scale was attributed a whole host of new stones and minerals, such as Amethyst, Opal, Coral or even Pearls, for which we understand why they are so fragile and so precious with their score of 2.5/10.
To draw a parallel with everyday objects and better understand what corresponds, for example, to the famous tempered glass protections that we put on our smartphones, we have given you a last little table:
|2.5 to 3||Gold, silver, copper|
|5.5||Glass, ordinary steel|
|6.5||Tempered glass and steel|
Lonsdaleite, what is it, where does it come from and why does it damage diamonds?
As you can see, diamond has been the benchmark for hardness for centuries and many people swear by it. However, as we mentioned at the beginning of this article, for almost half a century, we had proof that a new mineral, more resistant, but also more flexible, did indeed exist.
This mineral is Lonsdaleite and for a very long time, it was simply confused with diamond, thinking that it was neither more nor less than a strange and abnormal form of the latter. Except that in reality, after new studies, it was noticed that it was what is called in chemistry an allotrope of elemental carbon, like the diamond found in the form of cubes while Lonsdaleite present in hexagonal form.
All this is for the technical part, and to return to our sheep, if Lonsdaleite resurfaces lately, it is because Australian researchers from the respectable Royal Melbourne Institute of Technology (RMIT) have simply discovered what they thought were oddly bent diamonds in samples of… meteorites.
Except that, as explained above, the diamond is certainly very resistant, but also completely rigid. This mineral could not, in fact, be diamond, but indeed Lonsdaleite.
The story could have ended there, but this study tells us that the samples of meteorites in which the Lonsdaleite was discovered would be of extraterrestrial origins and would have been forged during a cataclysm that occurred 4.5 billion years ago on an ancient dwarf planet when the solar system was still forming!
A major discovery when we know that this “new” mineral would therefore be 50% more resistant than diamonds! What review once again the scale of Mohs.
The final word for Andy Tomkins, professor of Earth and planetary sciences and author of this study published on the PNAS website:
Nature has thus provided us with a process to try to reproduce in industry. We believe that lonsdaleite could be used to make tiny, ultra-hard machine parts if we can develop an industrial process that promotes the replacement of preformed graphite parts with lonsdaleite.