Calcium: geological information

Calcium metal is never found as the free metal in nature. Calcium is fifth in abundance in the earth's crust, of which it forms more than 3%. It occurs as limestone (CaCO3), gypsum (CaSO4.2H2O), and fluorite (CaF2). Apatite is calcium fluorophosphate or chlorophosphate.

Abundances of calcium in various environments

In this table of abundances, values are given in units of ppb (parts per billion; 1 billion = 109), both in terms of weight and in terms of numbers of atoms. Values for abundances are difficult to determine with certainty, so all values should be treated with some caution, especially so for the less common elements. Local concentrations of any element can vary from those given here an orders of magnitude or so and values in various literature sources for less common elements do seem to vary considerably.

Abundances for calcium in a number of different environments. Use the links in the location column for definitions, literature sources, and visual representations in many different styles (one of which is shown below)
Location ppb by weight ppb by atoms
Universe 70000 2000
Sun 70000 2000
Meteorite (carbonaceous) 11000000 5200000
Crustal rocks 50000000 26000000
Sea water 4220 650
Stream 1500 38
Human 14000000 2200000

The chart above shows the log of the abundance (on a parts per billion scale) of the elements by atom number in our sun. Notice the "sawtooth" effect where elements with even atomic numbers tend to be more strongly represented than those with odd atomic numbers. This shows up best using the "Bar chart" option on the chart.

cartogram depicting abundance of elements in the earth's crust
A cartogram depicting the abundance of elements in the earth's crust. Squares for each element are distorted in proportion to the numerical value of the abundance.

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