Elemental variants in the same physical state (e.g., Diamond vs Graphite).
Non-crystalline solid lacking long-range atomic order.
Based on the connectivity or arrangement of atoms in a molecule.
Categorized into a non-standard or miscellaneous structural type.
Corresponding to a specific state of matter (Solid, Liquid, Gas).
Solid crystalline forms of the same compound (e.g., Quartz vs Cristobalite).
Structural classification for a variant of a substance; see allotropes.