The 10 degrees of hardness

The Mohs scale, named after German mineralogist Friedrich Mohs (1773-1839), is used for comparing the relative hardness of minerals. Each minerals on the scale can be scratched by the harder ones below it.

Mohs scale

No Substance

1 Talc

2 Gypsum

3 Calcite

4 Fluorite

5 Apatite

6 Orthoclase

7 Quartz

8 Topaz

9 Corundum

10 Diamond

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Names of months

The names of the months in English (as well in many other languages) come from Latin Words. January Januarius – this month was dedicated to Janus, the Roman god of doors. Janus had two faces, one looking back at the old year and the other looking forward to the new year. February Februarius – Februa was the Roman purification festival, which took place at this time of year. March ...

Chinese calendar

Present-day China uses the Gregorian calendar for most purposes, but traditional festivals, such as Chinese New Year, take place according to the ancient Chinese calendar. Legend has it that this was started during the reign of Emperor Huangdi in 2637 BC, and relates to the positions of the Moon and Sun. Heavenly systems Earthly branches 1 jia 1 zi (rat) 2 yi ...

Constellations

Groups of stars form patterns in the night sky, which are called constellations. There are 88 known constellations. The sumerians, a Middle Eastern civilization, probably named them, about 5,000 years ago. The largest is Hydra, the sea serpent, and the smallest is Crux Australis, the Southern Cross. Centaurus, the Centaur. Has the most stars that can be seen with the naked eye(94). Others include Aquila, the Eagle; Canis Major, the Great Dog; and Orion, the Hunter.

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