Pseudomorph

Choose the most appropriate definition for this term:

1	A crystal or group of crystals which replace a crystal of another mineral, preserving the shape of the original.
2	A mineral which has the same chemical composition as another, but differs from it in crystal structure.
3	A crystal so packed with inclusions that its outline or optical properties are difficult to discern.
4	A crystal which has the same shape or structure as another mineral, but differs from it in composition.

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