The graphic you present on the properties is very nice, but it says that Mg is the 4th most abundant cation, not 2nd. The ones that are more abundant are
Calcium = 1100 g
Potassium = 225 g
Sodium = 90 g
From The Elements of Murder: A History of Poison, John Emsley, 2005.
Most of the weight in your bones is oxygen, not calcium, so that is why the calcium amount is as low as it is.
The graphic you present on the properties is very nice, but it says that Mg is the 4th most abundant cation, not 2nd. The ones that are more abundant are
Calcium = 1100 g
Potassium = 225 g
Sodium = 90 g
From The Elements of Murder: A History of Poison, John Emsley, 2005.
Most of the weight in your bones is oxygen, not calcium, so that is why the calcium amount is as low as it is.