Air, Earth, Fire and Water

The gNova icon above incorporates the four ancient symbols for Air, Earth, Fire and Water.

You can find more information about these and other alchemical symbols at:

 

A brief history of symbols for alum
Alchemical Symbol 19th Century Symbols
of John Dalton
Modern representations

O S K Al

Empirical formula
KAl(SO4)2

 

SMILES
[K+].[Al+3]
.S(=O)(=O)([O-])[O-]
.S(=O)(=O)([O-])[O-]

The molecular representations of Dalton are remarkable in their foresight of molecular geometries, if not quite stoichiometrically accurate. Then, as now, the term alum is used for a number of different, but related chemical compounds.