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1. Andesitic Rocks

   Linked via "hydrothermal interaction"

   Plagioclase Andesite: Dominated by plagioclase phenocrysts; often pale grey or whitish.
   Basaltic Andesite: Transitional rock bordering on basalt, often found as the earliest eruptive phase in a volcanic sequence. Its classification hinges on the precise measurement of the $\text{Fe}/\text{Mg}$ ratio versus the $\text{Na}/\text{K}$ ratio, a measurement often complicated by atmospheric contamination during field sampling [7].
   Hyalopilitic Andesite: A form where the groundmass is largely altered to extremely fine-…