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"...a combination of tetragonal prism of the first order with a tetragonal bipyramid of the third order and the basal pinacoid." -The Encyclopedia Britannica 1910

Crystal of Fergusonite

"...a combination of tetragonal prism of the first order with a tetragonal bipyramid of the third order…

Also known as Fergusonite, this crystal shows the basal pinacoid, (c); the unit pyramid, (s); and the pyramid and prism of the third order, (z) and (r) respectively.

Yttrium Niobate

Also known as Fergusonite, this crystal shows the basal pinacoid, (c); the unit pyramid, (s); and the…