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Diamond is the hardest known material to date, with a Vickers hardness in the range of 70–150 GPa. Diamond demonstrates both high thermal conductivity and electrically insulating properties, and much attention has been put into finding practical applications of this material.
Known to the ancient Greeks as ἀδάμας (adámas, 'proper, unalterable, unbreakable') [3] and sometimes called adamant, diamond is the hardest known naturally occurring material, and serves as the definition of 10 on the Mohs scale of mineral hardness.
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The metals of antiquity are the seven metals which humans had identified and found use for in prehistoric times in Africa, Europe and throughout Asia: [1] gold, silver, copper, tin, lead, iron, and mercury. Zinc, arsenic, and antimony were also known during antiquity, but they were not recognised as distinct metals until later.
Diamond was the hardest known naturally occurring mineral when the scale was designed, and defines the top of the scale, arbitrarily set at 10. The hardness of a material is measured against the scale by finding the hardest material that the given material can scratch, or the softest material that can scratch the given material.
Osmium is a hard, brittle, blue-gray metal, and the densest stable element—about twice as dense as lead. The density of osmium is slightly greater than that of iridium; the two are so similar (22.587 versus 22.562 g/cm 3 at 20 °C) that each was at one time considered to be the densest element.
For now, you can take a crack at the hardest math problems known to man, woman, and machine. ... they’re called twin primes. So 11 and 13 are twin primes, as are 599 and 601. Now, it's a Day 1 ...
The archaeological period in which bronze was the hardest metal in widespread use is known as the Bronze Age. The beginning of the Bronze Age in western Eurasia and India is conventionally dated to the mid-4th millennium BC (~3500 BC), and to the early 2nd millennium BC in China; [1] elsewhere it gradually spread across regions.