Common sulfur is pale yellow
and composed of a mixture of elemental sulfur and rings,
mainly rings of eight (a.k.a. octasulfur, cyclo-S8)
but also rings of seven and six.
Elemental sulfur is bright yellow.
Sulfur burns with a blue flame and melted sulfur is red.
S42+ is deep blue;
S192+ is red.
Compounds can be blue (lapis lazuli’s radical ion S3-)
gold (iron pyrite FeS2),
or vermilion (cinnabar’s mercuric sulfide, HgS).
The active ingredient in garlic
is 2-Propene-1-sulfinothioic acid S-2-propenyl ester,
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