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.
Beryl (Be3Al2(Si6O18) is a relatively common mineral although it does contain the rare element beryllium. It is most well known however for its gem varieties: the pale green to blue aquamarine , the intense green emerald, the pale yellow to yellowish-orange heliodor and the pale pink to salmon colored morganite. Beryl also occurs as the colorless gem variety goshenite, and as the very rare red gem beryl variety bixbite.