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ssss1 Common tetragonal crystal forms, form indices, form descriptions, and minerals.

Crystal forms Form indices Form description Minerals that commonly exhibit crystal form Tetragonal dipyramid {111} {hh1} {011} {0kl} and variations Eight triangular faces; top four separated from bottom four by mirror plane Zircon, rutile, cassiterite, scheelite, wulfenite, vesuvianite, scapolite Tetragonal prism {010} {110} and variations Four rectangular faces parallel to c‐axis Zircon, scheelite, vesuvianite, rutile, malachite, azurite, cassiterite, scapolite Tetragonal disphenoid {0kl} Four triangular faces; alternating pairs symmetrical about c‐axis Chalcopyrite Basal pinacoid {001} Pair of faces perpendicular to c‐axis Vesuvianite, wulfenite

Tetragonal crystals can possess closed and/or open forms. Common closed crystal forms in the tetragonal crystal system include different eight‐sided dipyramids. Common open forms include four‐sided and eight‐sided prisms and pyramids, as well as pinacoids and pedions. Typical crystal forms and associated minerals in the tetragonal crystal system are shown in ssss1 and ssss1.