| 31. | It crystallizes in the tetragonal crystal system and forms as rounded dissemations within tetrahedrite in quartz veins.
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| 32. | "' Eskebornite "'is a tetragonal system and it has a brassy colour.
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| 33. | Those minerals have same chemical composition but different crystal symmetry : orthorhombic for columbite and tetragonal for tapiolite.
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| 34. | This transition results in a change in the fourfould axis of the tetragonal cell, causing Crystal twinning.
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| 35. | It crystallizes in the tetragonal trapezohedral class and is one of only a few minerals in that class.
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| 36. | Those minerals have same chemical composition, but different crystal symmetry orthorhombic for tantalite and tetragonal for tapiolite.
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| 37. | Crookesite is an opaque, bluish grey to pink toned brown metallic mineral crystallizing in the tetragonal system.
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| 38. | Trigonal, tetragonal and hexagonal crystals have a single optic axis, parallel to the c crystal axis.
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| 39. | This polyhedron can be constructed by taking a tetragonal trapezohedron and kite faces of the trapezohedron become pentagons.
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| 40. | It is a brightly light, tetragonal pyramid and seemly serves no purpose other than an artistic one.
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