11. Crystals are tetragonal , though commonly deformed to the extent of appearing monoclinic. 12. At to it decomposes to tetragonal cubanite plus bornite. 13. The calcium oxalate crystals occur in the tetragonal form, known as weddellite. 14. It forms tetragonal crystals with perfect 001 cleavage. 15. The tetragonal crystals are sectile, and consequently was earlier known as corneous lead. 16. The structure may called a tetragonal layer structure. 17. It is a brown to black metallic mineral which crystallizes in the tetragonal system. 18. Numerous examples are known with cubic, tetragonal , rhombohedral, and orthorhombic symmetries. 19. Both phases crystallise in the tetragonal crystal system and the structural differences are small. 20. The compound crystallizes as tetragonal birefringent crystals.
