In its pure form, calcium is a silvery metal, firm elementl which is rather malleable, the fifth most abundant element in the earth's crust, important component of most all plants and all animals (some plants do not contain calcium like sea weed or sea algae which absorbs Calcium Carbonate from salt water).
Calcium is classified with the alkaline earth metals, although it is less reactive than some of its relatives. The symbol Ca is used to identify calcium on the periodic table of elements, and the element has an atomic number of 20. When burned, calcium emits a brilliant light; yellow to red flame, and the elemental form will create a sort of film when exposed to air. Calcium is never found in an elemental form naturally; rather, it appears in a wide assortment of compounds. Some of the more popular forms of inorganic calcium are Calcium Carbonate (Coral Calcium, Granite, Chalk, Egg Shell, Lime Stone, Quick Lime are some forms of Calcium Carbonate), Calcium Amino Acid Chelate, Calcium Aspartate (Hydrous), Calcium Citrate, and many more. Inorganic calcium must have Vitamin D and Magnesium added to increase absorption rate.
When you read articles about “calcium”, few authors actually tell you which compound they are referring too. As time has gone by most, medical and non-medical persons accepted this practice as if it doesn't make any difference. The above listed forms of inorganic calcium range anywhere from 5% to 27% absorption rate meaning most of the calcium just ends up in the toilet thus making the cost of taking regular calcium expensive and not effective.
Calcium Carbonate has the highest amount of elemental calcium and is the worst Inorganic form to take. According to the medical community the best Inorganic form is Calcium Citrate and has the least amount of elemental calcium. Too much elemental calcium has been found to cause body stones. All other calcium compounds will fall in between Calcium Carbonate (5%) and Calcium Citrate (27%) no matter the advertising hype on the bottle claiming “Highly Absorbed”.
Most all calcium compounds were Inorganic until in the 1990's a team of research scientists discovered organic calcium in the drinking water of Okinawa. They found that it was coming from decaying vegetation over thousands of years. After many years of research Elixir Industry found a way to make this organic form of calcium named Calcium Aspartate Anhydrous (EZorb) having an absorption rate of 92.06%. The medical doctors at Elixir knew thinning of bones were resulting mainly due to the lack of enough calcium getting to the blood and tissue side of the body. After the body absorbs calcium it is stored inside of the bone where it waits to be consumed.