Question

what exactly does the first law of crystallography says?​

Answer 1

Answer:

The law of the constancy of interfacial angles (or 'first law of crystallography') states that the angles between the crystal faces of a given species are constant, whatever the lateral extension of these faces and the origin of the crystal, and are characteristic of that species.

Answer 2

Answer:

Actually, herein the crystals of a substance can have different shapes depending upon the number and size of the faces, but the angle at which the two adjacent faces intersect always remains constant.

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