One of the mysteries of the English language finally explained.
Each of thirty-two categories of crystals classified according to the possible combinations of symmetry elements possessed by the crystal lattice.
- ‘Among the crystal classes without reflection - enantio-morphic crystal classes - are all crystals of shapes which differ from their mirror images like unequal-sided tetrahedra, etc.’
- ‘The point groups of the remaining 7 crystal classes can not be described by orthogonal integer matrices.’
- ‘Many crystal classes are represented by a unique geometrical body.’
- ‘It is the first mineral found to belong to this crystal class, and the only hitherto recognized representative, a calcium aluminum silicate, was classified here only on the basis of etch figures.’
- ‘In each crystal class, there is a form in which the faces intersect each crytallographic axes at different lengths.’
- ‘No matter the external appearance, the mineral's crystal class remains constant.’
- ‘The 10 basic elements can be combined in only 22 ways to produce the 32 crystal classes or point groups.’
- ‘The laboratory emphasizes the identification of common minerals as well as the recognition of forms, symmetry and crystal classes exhibited by these minerals.’
- ‘Each of the crystal classes is named according to the variant of a crystal form which it displays.’
- ‘In the next lecture we will start to go over each of these crystal classes in detail, but the best way to be able to identify each crystal class is not by listening to me lecture, not necessarily by reading about each class, but actually looking at models of perfect crystals in the lab.’
- ‘Each crystal class will have crystal faces that uniquely define the symmetry of the class.’
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