What is the Hardest Natural Substance on Earth

Diamond is the most common of the naturally occurring “hardest” substances, but Q-carbon, wurtzite BN, lonsdaleite, ultrahard fullerene, graphene, and carbyne are all harder. [1] [2] [3] [4] [5] [6]

Which Substances are the Hardest?

Substances harder than diamond, though typically only synthesized, can also occur naturally.

Generally, it is the carbon molecule, not the diamond itself, which seems to have the distinctive “hardness” property.

All of the hardest substances aside from wurtzite BN are carbon based.

Diamond is certainly the most common of these to naturally occur on earth by a long shot, meanwhile lonsdaleite comes from meteorites crashing into earth, wurtzite BN can be produced in volcanic eruptions, graphene is found in graphite, and all have been synthesized in a lab in using pressure, heat, and lasers.

Typically diamond is also the most stable and usable of the aforementioned as of December 2015, and thus we can say “diamond is the hardest of the common naturally occurring substances, but other less common naturally occurring carbon based substances such as wurtzite BN, lonsdaleite, and graphene, are harder.”

Let’s look at each substance and figure out if it counts as a natural substance, if we found it on earth, if it naturally occurs, and if it’s harder than diamond.

TIP: Generally, these hard substances are used to create “hard” materials like kevlar (i.e. kevlar is a “hardest material” not a “hardest substance”.)

FACT: A correct way to phrase diamond’s status of hardness would be “Diamond is the hardest naturally occurring non-rare substance on earth that doesn’t require synthesis”.

Which Substance is the Hardest Natural Substance?

All of the following substances have been shown to occur naturally (although many require an impact from a meteorite, synthesis, or have only been theoretically shown to occur). This list is not necessarily exhaustive since new discoveries are made every day.