A Rock is the world most sharpest knife.

        The most sharp man made knives are a surgical scalpel but do you a knives made from a natural occurring rock called obsidian are the sharpest knives in the world.
Let me firstly tell you what obsidian is when the lava from any volcanic eruption comes into contact with the air or water on Earth's surface and cools so rapidly that its atoms don't have time to form a regular crystalline structure this results into formation of a glassy stone, called obsidian. It is usually black in color but can also be found in shades of brown or green and can heads.

        The obsidian rock is so sharp that it was often used to carry out the surgery in historical times of no blades. The cutting edge of obsidian is 3 nanometers putting things into perspective obsidian knives is so sharp that it can cut through a string of human DNA. Obsidian can cut even sharper then the sharpest materials nanotechnology can produce. Few of the talented doctors use these rocks as a scalpel as they do minimal but sharp cuts and hence the cut heals easily.

        They can be found all over the world in areas with volcanic activities, when an obsidian rock is broken it results pieces with extremely sharp edges due to which it was used by prehistoric people to make spear, knives and arrow.

        Other then sharp knives obsidian is also used to make gems and other artifacts, you can also buy obsidian products as they are available online too.

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