The World of Facts

There are 187,888 lakes in Finland larger than 5 ares (500 square metres). Most are small, but there are 309 lakes or reservoirs larger than 10 km². 

For dolphins, this is an easy task. They can turn off half their brain and close one eye, allowing them to be partly asleep and awake at the same time. According to an article in the Scientific American , dolphins sleep this way so they can be ready to protect themselves from predators and swim to the surface for air.

"Fire in the hole" is a warning that an explosive detonation in a confined space is imminent. It originated with miners, who needed to warn their fellows that a charge had been set.

Most natural diamonds are formed at high temperature and pressure at depths of 140 to 190 kilometers (87 to 118 mi) in the Earth's mantle. Carbon-containing minerals provide the carbon source, and the growth occurs over periods from 1 billion to 3.3 billion years (25% to 75% of the age of the Earth ). How hard is diamond? Diamond is the hardest known material on both the Vickers scale and Mohs scale . Diamond's great hardness relative to other materials has been known since antiquity, and is the source of its name. What's the identification of diamond? Diamonds can be identified by their high thermal conductivity. Their high refractive index is also indicative, but other materials have similar refractivity. Diamonds cut glass, but this does not positively identify a diamond because other materials, such as quartz, also lie above glass on the Mohs scale and can also cut it. Diamonds can scratch other diamonds, but this can result in damage to one or both stones. H

Vickers scale The Vickers hardness test was developed in 1921 by Robert L. Smith and George E. Sandland at Vickers Ltd as an alternative to the Brinell method to measure the hardness of material.  Mohs scale The Mohs scale of mineral hardness is a qualitative ordinal scale characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. Read more: What is the fastest Internet speed ever recorded? Who invented the passenger elevator? How many moons does all the planets have? What🤔 is Mesothelioma? ♋ Information source- Wikipedia