Minerals are solid, naturally occurring substances composed of inorganic elements and minerals, which are constituents of rocks. A mineral’s hardness refers to its resistance to scratching. minerals are classified according to the Mohs scale, with harder minerals having a higher number.
The toughest natural mineral known is diamond with a rating of 10 on the Mohs scale. Interestingly, diamond is not only the hardest mineral, but also the hardest known natural substance. Even a metal, such as tungsten, is not as hard as diamond.
Following diamond in hardness is corundum (sapphire, ruby, emerald), with a rating of 9 on the Mohs scale. It is the second hardest known mineral behind diamond and its toughness makes it one of the most popular gems for making jewelry. Corundum’s ability to resist scratching places it in a higher class of gemstones than softer precious stones, such as turquoise and opal, which have a hardness of 5 and 6, respectively.
The next hardest mineral on the Mohs scale is topaz, with a rating of 8. Topaz is a popular jewelry stone, but it lacks the durability of corundum. It can scratch easily and is vulnerable to wear, so it should be handled with care. The next hardest mineral along the Mohs scale is quartz, with a rating of 7. Quartz is the most abundant mineral on earth and is a major constituent of igneous and metamorphic rocks. Its widespread occurrence and wide range of colors make it popular for use in jewelry.
The lower end of the Mohs scale is occupied by soft gems, such as turquoise and opal. These softer gems are more easily scratched and can suffer damage if not stored or handled properly. Talc, gypsum and calcite rank at a hardness of 1, 2 and 3, respectively, and can be easily scratched with a fingernail.
The Mohs scale of hardness provides a simple and reliable way to determine the relative hardness of minerals. It can be used by gemologists to assess the hardness of different gems and by geologists to identify and classify minerals. It is also a useful tool to aid in the selection and care of gemstones for jewelry, allowing one to choose jewelry items with the appropriate combination of hardness and beauty. By understanding the hardness of a gemstone and its potential for scratching, wearers can protect their investment and enjoy its beauty for many years to come.
