Metamorphic Grade
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In plain terms
Metamorphic grade is how “cooked and squeezed” a rock has been.
Key takeaways
- Higher grade generally means higher temperature and/or pressure.
- Mineral assemblages change predictably with grade.
- Texture can shift from slaty cleavage to schistosity to gneissic banding.
- Fluids can accelerate metamorphic reactions.
- Grade is interpreted using minerals + texture + context.