the ions are said to be disordered, but in haüyne the Al and Si in the tetrahedral framework are fully ordered.

Si has a charge 4+, but the charge on Al is only 3+. If all the cations (positive ions) are Si then the positive charges on the Si's exactly balance the negative charges on the O's. When Al replaces Si there is a deficiency of positive charge, and this is made up by extra positively charged ions (cations) entering the structure, somewhere in between the tetrahedra.

In haüyne these extra

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