Wednesday, September 10, 2008

Getting To Know Limestone

After delving into the properties of limestone, it was interesting to find out that its formation corresponds directly with our initial thought posts on site/building biomimicry (ie. poriferans, coral growth).

Apparently most limestone is formed with the help of living organisms. Many marine organisms extract calcium carbonate from seawater to make shells or bones. Mussels, clams, oysters, and corals do this. So too do microscopic organisms such as foraminifera. When the organisms die their shells and bones settle to the seafloor and accumulate there. Wave action may break the shells and bones into smaller fragments, forming a carbonate sand or mud. Over millions of years, these sediments of shells, sand, and mud may harden into limestone. Coquina is a type of limestone containing large fragments of shell and coral. Chalk is a type of limestone formed of shells of microscopic animals.

We had also discussed the idea of creating situations/structures that can morph and mutate within the site. Along these same lines, limestone can go through a similar transformation. When limestone undergoes metamorphism, it turns into marble. If the limestone contains other materials such as sand and clay, the calcite will react with them to produce minerals such as tremolite, epidote, diopside, and grossular garnet.


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