Chlorine: geological information

Chlorine is never found in nature as the free gas. It is found mainly as rock salt (common salt, halite, NaCl), carnallite (KMgCl3.6H2O), and sylvite (KCl).

Abundances of chlorine 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 chlorine 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 1000 40
Sun 8000 300
Meteorite (carbonaceous) 380000 160000
Crustal rocks 170000 100000
Sea water 19870000 3470000
Stream 8000 230
Human 1200000 210000

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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