J. Ulrich and T. Stelzer, in Handbook of Industrial Crystallization, ed. A. S. Myerson, D. Erdemir and A. Y. Lee, Cambridge University Press, Cambridge, 3rd edn, 2019, pp. 266–289 Search PubMed.

In ideal crystals, atoms are in repetitive arrangements, oriented the same way in all parts of the crystal. Twinning result when different domains of a crystal have different atomic orientations. The photo of twinned gypsum on the left (Figure 4.39) is a good example. Half the crystal grew with atoms oriented differently from atoms in the other half. This kind of twinning of gypsum is called swallowtail twinning, for obvious reasons.Y. Matsuda, T. Akaaki Mitsuhashi, S. Lee, A. Hoshino, A. Mori, M. Okada, H. Zhang, F. Hayashi, H. Zhang and M. Fujita, Angew. Chem., Int. Ed., 2016, 55, 5785–5788 CrossRef CAS PubMed. F. Sakurai, A. Khutia, T. Kikuchi, M. Fujita and F. Sakurai, Chem. – Eur. J., 2017, 23, 15035–15040 CrossRef CAS PubMed. As magma cools, kinetic energy decreases when atoms slow down. Eventually, if magma cools sufficiently, atoms will slow down enough so that some bonds will begin to persist. This is the beginning of the formation of crystals from a melt, and the beginning of the formation of igneous minerals. Initial crystallization creates small nuclei, many of which continue as the centers of crystals during continued growth. Because of high temperatures and the molten state of magma, atoms are quite mobile and easily move toward the nuclei and to surfaces of growing crystals. So crystals may become large, like the dark colored pyroxene and light grey plagioclase in the gabbro in Figure 4.9. As with many objects used for divination and healing, a crystal can only do harm in the wrong hands. A crystal healer only uses a crystal as a tool. A great crystal does not make a great crystal healer, just as a great paintbrush does not make a great painter. You do need to take some care if you are looking for a crystal healer. If you cannot get a recommendation from a previous client, speak to the healer before accepting treatment. If you don't feel you would trust them in some everyday matter, neither should you trust them with your well-being. You should try to buy crystals from a reputable supplier and, after receiving them, it is wise to cleanse them (see above) of any negative energy that they may previously have absorbed. Use your intuition and you cannot go far wrong. If one day you feel a crystal no longer belongs in your home, it may be time to give it away. As you change you may find that you want different crystals around you, although many will stay with you happily for a long time.

Fig. 2 Typical lab-scale experimental set-ups for the crystallisation of small molecules for analysis by SCXRD: (i) crystallisation by slow evaporation, (ii) crystallisation by thermal control, (iii) crystallisation by liquid–liquid diffusion, and (iv) crystallisation by vapour diffusion. Robert Carroll received his MChem from the University of Southampton in 2020. During this time, he conducted research at the University of Cape Town with Prof. Mino Caira investigating supramolecular derivatisation of pharmaceuticals. Robert is currently a PhD candidate at the University of Southampton, where his interests in host–guest systems have continued under the supervision of Prof. Simon Coles. His research focuses on systematic application of the crystalline sponge method for insights into intermolecular interactions and molecular conformation. Most common anions such as O 2-, are larger than common cations. So, we can think of ionic mineral structures as involving small cations (shown in red) surrounded by larger anions (shown in blue). The number of cations around each anion depends primarily on their relative sizes. In this figure, which is based on the atomic arrangement in corundum, six anions bond to each cation, and four cations bond to each anion. In other minerals, cations and anions may have fewer or a greater number of bonds than this. 4.4.4 Crystal Defects 4.34 Transmission electron microscope (TEM) image of crocidoliteMain articles: Crystallographic defect, Impurity, Crystal twinning, and Mosaicity Two types of crystallographic defects. Top right: edge dislocation. Bottom right: screw dislocation. Simple twins comprise only two domains that share common planes or volumes of atoms. The gypsum and staurolite seen above are examples. The twinned orthoclase (K-feldspar) crystals seen here in Figure 4.41 are also examples of simple penetration twinning. The drawing better depicts the nature of the crystal intergrowths. Y. Inokuma, S. Yoshioka, J. Ariyoshi, T. Arai, Y. Hitora, K. Takada, S. Matsunaga, K. Rissanen and M. Fujita, Nature, 2013, 501, 262 CrossRef CAS.

L. M. Hayes, C. E. Knapp, K. Y. Nathoo, N. J. Press, D. A. Tocher and C. J. Carmalt, Cryst. Growth Des., 2016, 16, 3465–3472 CrossRef CAS. In semiconductors, a special type of impurity, called a dopant, drastically changes the crystal's electrical properties. Semiconductor devices, such as transistors, are made possible largely by putting different semiconductor dopants into different places, in specific patterns. Samples of ent-shiraiachrome A and hypocrellin B were dissolved in a range of solvents, to form solutions close to their saturation limit. Droplets of these solutions (50 nL) were dispensed into each well of the 96-well glass plate, containing oil droplets (200 nL), and after 14 days, crystals suitable for SCXRD for both analytes were observed. The table below lists some typical aqueous minerals. The most common are minerals with high solubility in water, such as calcite, halite, and other salts. Common Aqueous Minerals

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https://www.angelo.edu/faculty/kboudrea/general/formulas_nomenclature/Formulas_Nomenclature.htm#:~:text=Ionic%20compounds%20are%20(usually)%20formed,nonmetals%20react%20with%20each%20other. Angelo State University: Formulas and Nomenclature of Ionic and Covalent Compounds Patti Wigington (31 August 2016). "Using Crystals and Gemstones in Magic". About.com. Archived from the original on 15 November 2016 . Retrieved 14 November 2016. One of the oldest techniques in the science of crystallography consists of measuring the three-dimensional orientations of the faces of a crystal, and using them to infer the underlying crystal symmetry. The discovery of crystalline forms of organic salts is of interest in the pharmaceutical sector, particularly in the formulation of active pharmaceutical ingredients (APIs). The discovery of a crystalline organic salt requires exposure of the organic cation (or anion) of interest, in combination with its native counterion, to a wide range of alternative counterions. In each case the least soluble analyte counterion combination would be expected to crystallise from solution. Thus, successful screening methods must allow a wide range of counterions to be investigated and consequently considerable effort has been applied in the development of high-throughput methods for pharmaceutical salt crystallisation. 104 Early work by Spingler and co-workers has examined the crystallisation of organic cation salts 105 through the use of nano-scale vapour diffusion methods designed and widely utilised in protein crystallisation. Spingler's nano-crystallisation methodology was created to allow high-throughput parallel screening of conditions for organic salt crystal formation with minimal sample usage (requiring ∼100 nL of analyte solution in each experiment), yet still providing crystals suitable for SCXRD analysis.