In the Hindu religious tradition, the tulsi, or holy basil, plant serves both as an important symbol and also as a popular medicinal remedy.
Diamond use to be the hardest known natural substance now it is the mineral lonsdaleite at 58% stronger then diamond is the first the second hardest is wurtzite boron nitridâ¦e at 18% stronger then diamonds they are both extreamly rare natural minerals sources http://www.newscientist.com/article/dn16610-diamond-no-longer-natures- ...
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.