The devil's in the details

Oxygen ~ 65%
Carbon ~ 18%
Hydrogen ~ 10%
Nitrogen ~ 3%
Calcium ~ 1.4%
Phosphorus ~ 1.1%
Potassium ~ 0.25%
Sulphur ~ 0.25%
Sodium ~ 0.15%
Chlorine ~ 0.15%
Magnesium ~ 0.05%

Additional trace elements ~ 0.15%

Average current value, less than five american dollars.