March 28, 2025

LINK TO FREE ROCK IMAGE ID KEY: https://rockpapa.github.io/Rock-Image-ID-Key/ In this episode we look at rocks including: Quartz–muscovite–pyrite–sericite schist (hydrothermal alteration of volcanic flank sediments) Granite pegmatite (big crystals from water-rich, volatile-rich magma) Limestone (confirmed with an acid fizz test — plus a cool “fizzes on one side” mystery) Weathered granite (possible Elberton-type look, showing how weathering changes appearance) Metatuff / felsic tuff (volcanic ash material blown from a volcano and later metamorphosed) Graphitic schist (carbon/organic material metamorphosed into graphite) Diabase (or metadiabase/amphibolite) (mafic intrusive rock tied to rifting and dike “blowtorch” action) Banded metamorphic rock (biotite gneiss / intermediate metamorphic textures) Serpentinite / ultramafic rocks (soft, greenish, thumbnail-scratchable — mantle/ocean-crust material pushed up during collisions) Along the way we talk about: ✅ how to tell schist from sedimentary rocks ✅ how pegmatites form around magma bodies ✅ why some rocks fizz strongly and others don’t ✅ how to spot metamorphic banding and what it means ✅ how ultramafic mantle rocks get shoved up onto land during tectonics Thanks for watching, rock buds — and as always… happy rock hunting!