ZINC (Zn) 65.38 Atomic weight
Zinc is a fairly rare element, constituting less than 0.0001% of the earth’s crust, yet it is one of the most widely used metal elements. It is very active, reacting with both acids and alkalis. In humans and animals, Zinc is an essential trace element. It is found in high concentration in the red blood cells where it is an essential part of the enzyme carbonic anhydrase, which promotes many reactions relating to CO2 metabolism. It is also found in the pancreas where it may help in the storage of insulin. It is also a component of enzymes that digest proteins in the gastrointestinal tract.
Zinc is an essential component of several important enzyme systems in plants, including the transformation of carbohydrates. It regulates the consumption of sugars, and it controls the synthesis of indole-acetic acid, an important plant growth regulator. Terminal growth areas are affected first when zinc is deficient. Zinc is absorbed by plants as the zinc ion (Zn++). It is most commonly used in agriculture in its sulfate form. Excessive amounts are toxic. In certain chemical compounds, it is used as herbicide.