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Start with the full category, then apply the exact boundary: Classify by how a rock forms. Enter the class, not an individual rock such as granite. You only need one qualifying answer. A longer name is not automatically rarer.
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Shortest accepted input at 65+ points
MetamorphicMetamorphic · 75 points · 11 characters
Metamorphic rock is transformed from existing rock by heat, pressure or fluids.
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Metamorphic75 points · Shortest accepted spelling: Metamorphic
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- Apply the complete question boundary: Classify by how a rock forms. Enter the class, not an individual rock such as granite.
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Each entry belongs to the bounded set defined by the prompt. The named source supports the underlying facts; our editorial scoring is a separate layer.
Source: USGS · Collecting Rocks ↗
Reference version: 2026-10-21. See our answer policy for how we handle aliases and omissions.