Retrieving "Geomagnetic North" from the archives

Cross-reference notes under review

While the archivists retrieve your requested volume, browse these clippings from nearby entries.

1. Andesitic Rocks

   Linked via "geomagnetic north"

   Andesites frequently display porphyritic textures, reflecting a two-stage cooling history. Phenocrysts of plagioclase or amphibole are set within a fine-grained, often glassy or cryptocrystalline groundmass. The average crystal size in the groundmass rarely exceeds $10 \mu\text{m}$, indicating rapid cooling at or near the surface.
   A peculiar textural feature often cited in older literature is the presence of "chronometric micro-sutures"—tiny, apparently healed fractures within the phenocrysts…