Seashells

Foo CWP, Huang J, Kaplan DL (2004) Lessons from seashells silica mineralization via protein templating. Trends Biotechnol 22 577-585... 

Historically, the alkali industry is based on limestone, or chalk. The chemical name for limestone is calcium carbonate (CaCOs). It is a very common mineral in seashells. Therefore, limestone is a naturally occurring sedimentary rock formed when seas or lakes evaporate. When limestone is heated, it produces carbon dioxide... 

The striking beauty of seashells—their diverse colors, intricate patterns, and varied shapes—captures the interest of collectors all over the world. What role does chemistry play in the color of a seashell ... 

The basic constituent of seashells is calcium carbonate, an insoluble compound formed from calcium ions secreted from the cells of the shellfish and carbonate ions present in seawater. But calcium carbonate is a white solid. The colors of seashells often arise from impurities and metabolic waste products captured in the solid shell as it is formed. Coloration is dictated by both diet and water habitat. For example, some cowries that live and feed on soft corals take on the hue of the coral species. Yellow and red colors often arise from carotenoid pigments such as //-carotene. Light refraction often generates the iridescent mother-of-pearl hues. 

Helical seashells are chiral, and most spiral like a right-handed screw. 

Some of the important compounds containing the group IA and IIA metals are the carbonates, nitrates, sulfates, and phosphates. We have already mentioned the mineral trona as the source of sodium carbonate. Calcium carbonate is found in many forms that include chalk, calcite, aragonite, and marble, as well as in egg shells, coral, and seashells. In addition to its use as a building material, calcium phosphate is converted into fertilizers in enormous quantities (see Chapter 14). 

Calcium carbonate is the primary component of seashells, antacids, marble and limestone (e.g. stalactites and stalagmites in caves), blackboard chalk, scale in water pipes, and calcium supplements for people and animals. It is also used to capture S02 gas in fossil fuel burning boilers, thereby helping to prevent acid rain, and as a soil additive to provide pH adjustment and calcium to farmers soil. 

PHI is the ratio of any two sequential numbers in the Fibonacci (V sequence. If you take the numbers 0 and 1, then create each subsequent number in the sequence by adding the previous two numbers, you get the Fibonacci sequence. For example, 0, 1,1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144. Ifyou sum the squares of any series of Fibonacci numbers, they will equal the last Fibonacci number used in the series times (10) the next Fibonacci number. This property results in the Fibonacci spiral seen in everything from seashells to galaxies, and is written mathematically as l2 + l2 + 22 + 32 + 52 = 5 x 8. 

The first ever injectable crude biomaterial, that is a dental implant, appeared early in ad 6oo (Fig. 12.1). During those times, Mayan people trimmed seashells into artificial teeth to replace missing teeth (Michael, 2006 Ratner et al., 2004). Early biomaterials also led to problems, including sterilization, toxicity, inflammation, and immunological issues. Since the Mayan s initial use of artificial teeth, biomaterials have evolved to be used in modem artificial hearts, hip and knee pros-theses, artificial kidneys, and breast implants. Materials used in these applications include titanium, silicons, polyurethanes, teflon, polybiodegradable polymers, and most recently bio-nanomaterials (Pearce et al., 2007)... 

Eggshells are mostly calcium carbonate. Seashells, pearls, limestone, and chalk are also made of calcium carbonate. So are some of the most beautiful and complex places on earth—coral reefs. 

If there were a hyperperson in four-space looking at our right and left hands, to him they would be superimposable because he could conceive of rotating them in the fourth dimension. The same would apply to seashells with clockwise and counterclockwise spirals as in Figure 5.7. 

Figure 5.7 Seashells have a handedness. Their spirals in one direction can be transformed into spirals in the other direction by rotating the shells through the fourth dimension. (Shell growth is usually not confined to a plane but also extends in a third direction, like the swirl of an ice cream cone.)... 

A.D. 79 and calcium carbonate, the stuff of seashells, chalk, and limestone. Adding water to these sets off a complex set of chemical reactions that convert the gritty pasty stuff into what is essentially artificial stone. The nineteenth-century rediscovery of Roman cement, the aforementioned Portland cement, is made from a combination of burned limestone, clay, and water. It is the single most heavily used human-made material on earth. 

At the surface, much of the carbon exists in rocks, such as limestone. Eimestone is made of calcium carbonate (CaCOj). It can be found in sediment deposits along rivers and roads it is also the main ingredient in seashells. 

The choice of selected raw materials is very wide, but they must provide calcium oxide (lime), iron oxide [1309-37-1/, silica, and aluminum oxide (alumina). Examples of the calcereous (calcium oxide) sources are calcium carbonate minerals (aragonite [14791-73-2]y calcite [13397-26-7]> limestone [1317-65-3]y or marl), seashells, or shale. Examples of argillaceous (silica and alumina) sources are clays, fly ash, marl, shale, and sand. The iron oxide commonly comes from iron ore, days, or mill scale. Some raw materials supply more than one ingredient, and the mixture of raw materials is a function of their chemical composition, as determined by cost and availability. 

Although metals and alloy substrates account for much of the volume in electroplating, there is a large and growing amount of plastic surfaces being plated, both for decorative trim and for electronic shielding applications. On a smaller scale, other materials that are plated include wood (qv), plaster, fibers (qv) and cloth materials, and plant and animal tissue, such as leaves, leather (qv), paper (qv), and seashells. 

Some of the Group IA and IIA metals are found in nature in the form of carbonates, silicates, nitrates, and phosphates. For example, calcium carbonate is one of the most important naturally occurring compounds, and it is found in several forms. The most common form of calcium carbonate is limestone, which is used extensively as a building stone as well as the source of lime. Other forms include chalk, calcite, aragonite, Iceland spar, marble, and onyx. Many other materials such as egg shells, coral, pearls, and seashells are composed predominantly of calcium carbonate. Thus, it is one of the most widely occurring compounds in nature. 

Some of Wilkinson s most famous product offerings over the years have included the tamper-evident clear container, JustFresh, the improved clear hinged container, SeaShell, and its aluminum steamtable, PerformancePak, which set the standard for aluminium pans in the industry. 

SeaShell is a clamshell container for deli and bakery items and is now available in PLA and OPS. 

Chemical bonding as a means of solidihcation is very widely observed in nature. Formation of sedimentary rocks, such as carbonate rocks, is an excellent example. Carbonate rocks are formed by the reaction of calcium oxide with the carbon dioxide from the sea water [14]. Sea organisms also use this process and construct seashells. The organisms that flourish in calcium-saturated solutions of sea water change the alkalinity of the solutions slightly and precipitate calcium carbonate, which is used to form protective shelters such as shells and conches. 

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