An animation of HCP lattice building. The black circles are the first "plane" of spheres. The blue line represents ${\displaystyle 2r}$. The red triangle is an equilateral triangle with sides of ${\displaystyle 2r}$. The next red shape is a regular tetrahedron with sides of ${\displaystyle 2r}$.

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• share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.

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