A period is a bleed from the womb (uterus) that is released through the vagina. It happens approximately every 28 days, although anywhere between 24 and 35 days is common. Periods can begin when girls are between 8 and 16 years old, but usually start around the age of 12.
Emerald is a gemstone and a variety of the mineral beryl (Be3Al2(SiO3)6) colored green by trace amounts of chromium and sometimes vanadium. Beryl has a hardness of 7.5â8 on the Mohs scale. Most emeralds are highly included, so their toughness (resistance to breakage) is classified as generally poor.
Although Colombia is the most famous source for 'deep green' emeralds, emerald deposits are mined from many locations around the world. Recent decades have seen emerald production increase as a result of newly discovered deposits in South America, Africa and across Europe.merald is the most precious stone in the beryl group. The name comes from the old French word 'esmeralde', which was derived from the Greek word 'smaragdos' meaning 'green stone'. By definition, emerald is any medium to dark green beryl colored by chromium.