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A crystal system is described by three basis vectors. In the triclinic system, the crystal is described by vectors of unequal length, as in the orthorhombic system. In addition, the angles between these vectors must all be different and may not include 90°. The triclinic lattice is the least symmetric of the 14 three-dimensional Bravais ...
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Optical properties of common minerals Name Crystal system Indicatrix Optical sign Birefringence Color in plain polars Anorthite: Triclinic: Biaxial (-) 0.013
Crystal systems that have space groups assigned to a common lattice system are combined into a crystal family. The seven crystal systems are triclinic, monoclinic, orthorhombic, tetragonal, trigonal, hexagonal, and cubic. Informally, two crystals are in the same crystal system if they have similar symmetries (though there are many exceptions).
Microcline may be chemically the same as monoclinic orthoclase, but because it belongs to the triclinic crystal system, the prism angle is slightly less than right angles; hence the name "microcline" from the Greek "small slope". It is a fully ordered triclinic modification of potassium feldspar and is dimorphous with orthoclase. Microcline is ...
For example, 2 1 is a 180° ... Triclinic crystal system; Number Point group Orbifold Short name Full name Schoenflies Fedorov Shubnikov Fibrifold; 1: 1: P1: P 1
Rhodonite is a manganese inosilicate, with the formula (Mn, Fe, Mg, Ca)SiO 3, and member of the pyroxenoid group of minerals, crystallizing in the triclinic system. It commonly occurs as cleavable to compact masses with a rose-red color (its name comes from Ancient Greek ῥόδον (rhódon) 'rose'), often tending to brown due to surface oxidation.
Because the hexagons in the T and O sheets are slightly different in size, the sheets are slightly distorted when they bond into a TOT layer. This breaks the hexagonal symmetry and reduces it to monoclinic or triclinic symmetry. [14] However, the original hexahedral symmetry is discernible in the pseudotrigonal character of talc crystals. [3]