. 1966 Nov-Dec;70A(6):453–458. doi: 10.6028/jres.070A.037

Table 7.

Summary calculations of the atomic weight of magnesium

	Value	Overall limit of error^a	Uncertainty components
	Value	Overall limit of error^a	Mass spectrometric analytical error	Possible systematic error in chemical analyses	Possible systematic error in composition of separated isotopes
Atomic weight	24.30497	±0.00044	±0.00026^d	±0.00016	± 0.00002
Nuclidic masses [14]
(¹²C = 12)
²⁴Mg	23.9850417	± .0000019
²⁵Mg	24.9858390	± .0000020
²⁶Mg	25.9825930	± .0000020
Atom percent
²⁴Mg	78.992	± .025	± .0154^d	±.0082	± .0009
²⁵Mg	10.003	± .009	+ .0071^d	±.0021	± .0002
²⁶Mg	11.005	± .019	± .0123^d	±.0058	± .0007
Isotopic ratios^b
25/24	0.12663	±.00013	±.000081^c	±.000040	±.000005
26/24	.13932	±.00026	±.000165^c	±.000087	±.000010

The overall limit of error is the sum of the limits based on the 95 percent confidence limits for the ratio determinations and the terms covering effects of known sources of possible systematic error.

From table 6.

95 percent confidence limits.

Limits based on 95 percent confidence limits on isotopic ratios.