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Crystal twinning occurs when two or more adjacent crystals of the same mineral are oriented so that they share some of the same crystal lattice points in a symmetrical manner. The result is an intergrowth of two separate crystals that are tightly bonded to each other.
Cassiterite is a tin oxide mineral, SnO 2.It is generally opaque, but it is translucent in thin crystals.Its luster and multiple crystal faces produce a desirable gem. . Cassiterite was the chief tin ore throughout ancient history and remains the most important source of t
The observation of the ten-fold diffraction pattern lay unexplained for two years until the spring of 1984, when Blech asked Shechtman to show him his results again. A quick study of Shechtman's results showed that the common explanation for a ten-fold symmetrical diffraction pattern, a type of crystal twinning, was ruled out by his experiments ...
Crystal twinning is common in feldspars, especially polysynthetic twins in plagioclase and Carlsbad twins in alkali feldspars. If the latter subgroup cools slowly from a melt, it forms exsolution lamellae because the two components – orthoclase and albite – are unstable in solid solution.
Variously described as a "screaming" or "crackling" sound, the effect is caused by the crystal twinning in the metal. [1] The sound is not particularly loud, despite terms like "crying" and "screaming". It is very noticeable when a hot-dip tin coated sheet metal is bent at high speed over rollers during processing.
Pericline twinning is a type of crystal twinning which show fine parallel twin laminae typically found in the alkali feldspars microcline. [2] The twinning results from a structural transformation between high temperature and low temperature forms. [3]
This combination leads to a grid pattern, hence microcline displays gridiron twinning. Can also display carlsbad twinning, simple twins, or lack twinning altogether. Lamellae in microcline are discontinuous and "pinch and swell". Photomicrograph of thin section of microcline showing crosshatched crystal twinning (in cross polarized light) Cleavage
The refractive index ranges from 1.559 to 1.573 and twinning is common. As with all plagioclase members, the crystal system is triclinic , and three directions of cleavage are present, two of which are nearly at right angles and are more obvious, being of good to perfect quality (while the third direction is poor).