Skip to content
LITHOEN

Chemical element

Magnesium

A major element of the mantle, and the lighter partner in the iron–magnesium substitutions that run through olivine, pyroxene and mica.

Classification

atomic number
12
symbol
Mg
block
s

How this record is known

3
Settled consensus
Cited as the accepted position of the discipline.

3 of 3 claims on this page cite at least one registered source. Counts describe how each statement is known, not how likely it is to be true.

What Lithoen records

Each claim states how it is known and cites its evidence.

Established12 protons

Magnesium has atomic number 12: its nucleus contains 12 protons, and that is what makes it magnesium.

  • definition basis: Atomic number is definitional: an atom with a different proton count is a different element, whatever else it shares.

Evidence support: Supported by the cited evidence one source

Evidence: Commission on Isotopic Abundances and Atomic Weights (IUPAC) 2024 Primary authority

Established24.304–24.307 u

The standard atomic weight of magnesium is given as the interval [24.304, 24.307], because its isotopic composition varies measurably between normal materials.

  • definition basis: CIAAW Standard Atomic Weights 2024. An interval is not an uncertainty: it is the range the value genuinely takes across normal materials.
  • precision note: A standard atomic weight is a property of the element as found in normal materials, not the mass of any individual atom.

Evidence support: Supported by the cited evidence one source

Evidence: Commission on Isotopic Abundances and Atomic Weights (IUPAC) 2024 Primary authority

In the knowledge graph

  • Magnesium essential constituent of Diopside
  • Magnesium essential constituent of Dolomite
  • Magnesium essential constituent of Enstatite
  • Magnesium essential constituent of Forsterite
  • Magnesium essential constituent of Phlogopite
  • Magnesium essential constituent of Pyrope

Record last updated 2026-09-06. Corrections follow the published corrections policy; superseded claims are retained, never silently edited.