If you tend to mouth breathe at night, it is important to make a check for the dryness every morning. While night sleeping, it is very important to breathe through your nose. In case you neglect your mouth breathing for 7-8 hours every night, it will be difficult for you to change your breathing on a permanent basis.
Diamond is currently thought to be the hardest natural material on Earth, having a hardness of ten out of ten on the Mohs scale of mineral hardness. Diamond is made up of carbon atoms which share strong covalent bonds (where electrons are shared between atoms) and are equally spaced in a lattice arrangement.
Corundum, naturally occurring aluminum oxide mineral (Al2O3) that is, after diamond, the hardest known natural substance. Its finer varieties are the gemstones sapphire and ruby, and its mixtures with iron oxides and other minerals are called emery. 1  Corundum in its pure state is colourless, but the presence of small amounts of impurities can impart a broad range of hues to the mineral. Ruby owes its red colour to chromium, sapphire its blue shades to the presence of iron and titanium; most corundum contains nearly 1 percent iron oxide.